The way this is worded I am 99.9 percent sure this is one of my friends trolling me, but I'll bite anyway even if it is, so strap in, because I have many messy, convoluted THOUGHTS. (in case it isn't sorry for presuming Anon and thanks for your question and being curious about my opinion)
The reason why I think this is a friendly troll ask is because you can't make this an or question and I have been very vocal about that in the past. I mean you can, Young Royals fandom is doing it all the time everywhere, but you shouldn't and yes I'll keep being nitpicky about that.
Why? Because In the context of monarchies and royalty the word abdication only applies to crowned monarchs and yes it does make a difference.
Let me use a (simplified) irl example: Harry didn't abdicate, William can't abdicate (yet), only Charles can and only now that he's king. Charles could have given up his rights to the throne in favor of William when he was still Prince of Wales, but that wouldn't have been an abdication, not if he had done it before becoming King himself.
The same is true for Wilhelm. Wilhelm can only abdicate after ascending the throne. If he's not king, it's not an abdication.
Yes I'll keep harking on about this until the end of my days, because while it might not seem like a big deal what word you use here, it actually makes a big difference legally and politically and on all levels if it's a crowned monarch and head of state formally abdicating or if it's an heir giving up their place in the line of succession.
So what we're actually all discussing here (most of the time) is should Wilhelm give up his place in the line of succession and right to the throne, and my immediate reaction to that (after no, never but also he's sixteen, it's way to soon for any of that) is, how and in what way?
We're all rooting for Wilhelm and want him to be happy, of course we are. Wilhelm is my absolute favorite, but I hate this trend in the fandom that's romanticizing what everyone likes to call "'Wille's abdication" or abolishing the monarchy in general, because just because "it's right", doesn't mean it's in any way easily or quickly done in a "haha and now Sweden no longer has a monarchy" kind of way. That's not how it works.
Don't get me wrong, I'll never romanticize the monarchy or any other systems enforcing hierarchies and inequality, not in irl nor in any of my fics. Tax billionaires until they aren't anymore, eat the rich and yes, of course get rid of all monarchies, but you can't just go "lol no longer a prince", especially when like Wilhelm, you're still a teenager and can't make a properly informed decision about what you're doing.
Now before you all come at me with pitchforks, of course teenagers can tell right from wrong and make informed decisions, but Wilhelm grew up not only with immense privilege, but also extremely sheltered and in a bubble. Yes he started out his first semester of 'high school' in a public school, but I promise you the majority of his classmates' parents weren't plumbers or tax accountants.
Wilhelm has no idea of real life, not even rich people real life. He doesn't go to the store or buy his own clothes, and neither do his parents, nor do they randomly go to restaurants or whatever. Wille has never been able to go out in public without being photographed and noticed and everyone making a fuss, and he has no idea how most things work because there's always staff doing everything for him quietly and in the background.
If, and I say if, Wilhelm is sure he wants to step back from his role, then he should still wait until his early to mid twenties before doing so, because doing so is complicated and not something he can change his mind about later. Also he needs to learn about normal life first.
But I digress. Lets say Wilhelm does want to give up the throne. He's brought it up himself as a possibility when he was still desperately trying to get Simon back in any way he could. That still makes him a prince and a duke.
He'd still be a member of the royal family/house (I hate how that seems to be used synonymously in English). Not being king wouldn't mean he wouldn't be expected to become a working member of the royal family once he's an adult, except now there'll be a different monarch, one he'll have to obey within the family hierarchy, and chances are it'll be August.
Okay, so we take this a step further. Wilhelm gives up his rights to the throne and doesn't become a working royal, but that would mean betraying his family (his words) and stepping away from them. Not just his parents but everything he's grown up with and everything he knows. And he'd still be a prince and a duke.
Wilhelm will never be Joe Average Wille (is Harry now? Was Diana? and neither of them were next in line), no matter how much he might want to, especially not after S02E06 and I know I've said it before but I'll say it again: he'll keep being hounded, he'll keep being seen as royalty, and the only thing that'll change is who pays for his security.
(which btw the security thing is no joke, I know Wilhelm has no Diana levels of celebrity yet, but he's now the first openly queer modern royal and heir to the Swedish throne, there will be significant international media interest and it will stay, especially now with smart phones being able to capture his every move, and I'm old enough to remember the shit show that happened when Diana no longer had official protection officers and police protection and it was not fun, hounded is an understatement and professional 24/7 security is expensive and private security will never be as good as those who also have government/Security Service resources)
Also I firmly believe that what Wilhelm hates is not being royalty or the future king, but being forced into a role, handed a script and expected to perform without any of his own input.
When that changes, and it will, his attitude towards it will also change.
People argue that he'll be happier once he gives up his place in the line of succession, but I disagree.
I think he might have been happier had he been born a normal kid, but also maybe not because then he'd be a very different person, so there's no telling, but he'd always live with the guilt of betraying his family and heritage, and people, both well meaning and not, will never let him forget that.
Yes he struggles now, and I don't want to make light of his struggles, but every teenager struggles with their identity and place in life and things will be different once he's grown up and more secure in himself.
My 'ideal' fantasy solution were this irl would be for Wilhelm to become the last King and to work with the government to ensure a smooth transition once he retires, because abolishing the Swedish monarchy is complicated, but do I think that'll actually happen? No. Because that's not the kind of person Wilhelm is.
Also Wilhelm has been born to immense wealth, privilege and soft power, all three of which he will to a degree keep all his life no matter what happens.
Of course he needs to put his own mental health and wellbeing first, and I'm aware that he never asked for any of this, but he still has it, and with that comes a duty, and I think it'd be absolutely selfish of him to just take that wealth, privilege and soft power and to let the "common people" deal with the mess he left behind, because let's not kid ourselves, if he announces he'll give up his throne tomorrow and sticks with it until he's eighteen and beyond, do you really think people in power won't do anything they can to keep the system in place?
Kristina loves her son and wants what's best for him, even if she's not the best parent, but she'll not dismantle the system for him.
She knew what August had done, and she still would've rather had him as heir instead of even so much as considering anything else.
The Royal Court most certainly won't, and even if the elected government wouldn't be opposed to getting rid of the monarchy (if, there's a chance but not a guarantee, depending who is in power when that happens), that's not the end of it.
You can't abolish the monarchy and keep the nobility, and there will be plenty of people, both obscenely rich and averagely well off people, who will do their utmost to keep their position of privilege.
It will not only become a matter of equality, Sweden is one of the most egalitarian countries in the world. It'll be about history and heritage and tradition.
It'll be a giant mess and if it wants any chance of succeeding, it'll need someone in power to actively work towards it, someone whose position the monarchists and traditionalists and conservatives respect, and that has to be a King Wilhelm, not a Crown Prince Wilhelm or a Prince Wilhelm or a Joe Average Wille who took his wealth and privilege and soft power and ran away because he chose to be selfish and leave a system in place no one was better able to do something about than him.
Now of course I'm once again talking about an adult Wilhelm, canon Wilhelm is still a teenager and shouldn't have to deal with or worry about any of that, and he gets to want to be selfish, because he's sixteen, but he won't always be sixteen, and when he isn't any longer his outlook will have changed as well.
Now we come to another point though, and that is that Wilhelm is not a revolutionary. He has his own head and a temper and doesn't want to blindly do as he's told, but he's not the kind of person who goes and topples a system.
I don't even think Simon is. He wouldn't mind the monarchy being abolished, sure, but I don't think he has the energy to become a political activist and to fight the system all his life, especially in a life without Wilhelm.
With Wilhelm it's different, there I'm sure he'll use the power he has for good. He'd be aware that he can change things and do his best to choose his engagements carefully should he become a member of the royal family.
That said, in time I don't think Wilhelm will mind being King, not if he also gets to be with Simon at the same time, and I don't think he should give up his place in the line of succession.
Finally, and most importantly, because we're talking about a TV show and a fic fandom here and not irl, I love playing with the idea of the Royal Court, the Swedish upper class, and all the conservatives and monarchists having to (figuratively) bow and scrape to an openly queer, headstrong monarch and the gay, biracial love of his life who also happens to be the son of a poor, immigrant single mother, because that is a very, very cathartic thought, and so yeah, King Wilhelm and Prince/Duke/King Consort Simon all the way, always.
That's what drew me to this show in the first place, a queer Crown Prince, and not a random queer teenager going about his normal life. There're plenty of other (great) shows for that.