Starlight Glimmer explained the situation to Trixie- her closest remaining confidant. Though Trixie mentions that she agrees that Starlight went a bit far being an ex-villain herself, Starlight dismisses it as she grabbed the books she took from the School of Friendship. Starlight had one request and one request only: That whoever becomes the Head of the School next be watched closely while she finds a way to regenerate her magic. Starlight had just enough to keep doing things like levitation and more basic spells, but not enough to do what she'd normally do- that went to Tirek.

Trixie hestitantly agrees for the sake of her friend, but... Even she can tell that something is very wrong, and she makes a secret pledge to herself to figure out what.

I'm going with the assumption that magic doesn't regenerate. I mean, otherwise Cozy stealing all the Magic from Equestria would be a lot less earth-shattering. Besides, not like we saw anyone else getting stronger after Tirek's first attack.
But now the Cynical Centaur story arc is done, and... Gotta admit, this isn't what I was expecting going into this but MAN am I glad how it turned out. In the mean time though, I think this'll be my last plot-driven thing for a little while. Wanna relax after creating this kinda story.