Yeah, maybe they both come back because Monica does die (because thats the only way any gallagher can finally accomplish something apparently) and Mickey knows Ian would want to be with his family for that, so he risks it. He’s prepared to leave Ian behind saying this is where he belongs. Maybe he catches a glimpse of Trevor (or maybe they actually talked while in Mexico and Mickey isn’t transphobic, just trying to understand why Ian would do better with something…tame). And maybe he also sees Yev and Svet and it really sinks in that there’s no way he could ever fit back into the Southside even if he weren’t a wanted man. And so he’s all ready to say goodbye for real this time. He’s accepted it, maybe he’ll make peace when he’s got a margarita in hand and the sun on his face…shit, maybe he’ll throw the trail off and go north……but there Ian is, catching him as he tries to sneak off without a word. Mickey tries really hard but this time it’s Ian who fights for them and he says he loves him, wants to be with him, thick thin sickness….criminalness…that’s not a word Gallagher…..but then Ian is kissing him and he says he made his choice…he made it a long time ago he’s just seeing it clearly now. Turns out he might have thought everything was bearable on his end, but his family has always been a mess whether he was involved or not…most of the time not, so why not go with the one thing that chose him back? And Mickey can’t fight him on it. It’s true. And he thinks it’s scary he chose Ian before Ian ever knew he’d choose him. So they kiss again, get back in the fifth stolen car. Ian looks at the house one more time but not long. And then they’re off. Never to return but that’s okay because they have each other.
And live happy forever