I'd say that Jeff's character hasn't changed much. I've recently been re-watching the first three seasons and it is abundantly clear that as the show progresses, that the only "good" that Jeff does is for the group, and no one else. Whenever he (or any other group member) tries to help an outsider, they wind up making things worse. Sort of creating an infinite loop for the characters. Why change if they know things are just going to turn out the same?

Annie, who has been replaced by Frankie doesn't have much of a place anymore in the group. In fact, I have a feeling that the whole "Frankie is a lesbian" idea sprung from the fear that people would interpret a Jeff/Frankie thing. Honestly, it's the only thing keeping me from thinking it.

Frankie has also replaced the Dean, and has found ways to control Jeff. What the hell is up with her? Who knows? Maybe the fact that she's absent in the most recent promo will feature a revelation about her character.

Abed, for the most part is even more of a wreck. He lost his best friend and has no direction whatsoever. The past few seasons, he's been increasingly fearful of "a finale" which seems to be the theme of the next episode. He's just riding things out until the end. He knows that their life IS just a show, and he's gonna keep going with the loop.

Britta kind of just gave up on herself.

For as Meta as the show is, I'm surprised it hasn't called out its recent lack of story arc progression. Jeff/Annie, "Save Greendale", Troy, Shirley, Pierce? Honestly, if anything I feel the flaw of this season is the lack of story progression, and character development. They're kind of stuck. And they know it.