Congrats on your paper getting an A. If only you could write for the show. Cause certainly the writers seem more intent on pulling every cliches and Gary Sue moment out of the book than doing original thoughtful writing (unless that plot happens to be the C plot, then it will be creative and unique...and drive the Chuckistans to new lengths of crazy).
I think Charlie became a regular because Jessica and Taylor are gone, or at least, very significantly reduced. It's too bad because Nate never gets a storyline yet all the guests stars do.
I wouldn't worry about Dair not happening. Given that it was the only thing that was universally praised this season (whereas Chair and Abusegate were only loved by the Gossip Girl Reality Index), I don't think the writers will abandon it that quickly. Especially given that was all Josh Schwartz tweeted for weeks on end. (And Bart150, a producer on the show, is pro-Dair. Not to mention, the ratings grew steadily during the Dair arc, but then collapsed when SuperChuck! and Chair happened.)
At any rate, I'm haven't watched the show since 4.20. After much internal debate, I've decided I'll youtube Dair. And on tumblr still post reblog my favorite Dair picspams and/or season 1-4 Blair/Serena fashion, but I'm not watching the show next season. My feminist principles might be very grey, but I'm I am not going to let Safran tell me what I saw wasn't/isn't abuse. (And the abuse was happening well before Chuck smashed the glass above Blair's head.)