Ahem. If I might make a prediction for Season Five.
Starswirl the Bearded is the overarching villain.
Why make such a bold claim? A few specific reasons. First, Starswirl’s Last Spell involved destinies, cutie marks, changing them around. Not necessarily for malicious ends, but disaster is what resulted, had Twilight not fixed it.
Secondly, the entire season’s theme is Cutie Mark Magic, which means the very nature of destinies and the cutie marks themselves will be examined and poured over in great detail.
Third, everything about the premiere episodes says we’re going to have villains who try to impose a Forced Harmony, a Forced Equality, an Order that is as dangerous and as destructive as Discord’s Chaos.
If any character we know would be prey to such a thing, it’d be Starswirl the Bearded. Oh, I don’t think he’d be intentionally trying to be evil for the sake of evil. I think he would have ends that he thinks are logical and reasonable, and he would be doing malicious and harmful things in trying to reach those ends.
It’d certainly result in a pretty spectacular confrontation. Starswirl would be a far harder enemy to defeat than any Twilight has gone up against. I don’t think a rainbow to the face would cut it this time.
So yeah. That’s what I think.