I'm betting that pretty much the entire core group will remain in tact. They'll lose Otis' wife, the suicidal girl, and the son that has seen almost no airtime.
I predict that Carol will be cornered by zombies and saved by Daryl. Herschel will agree to leave the farm after Rick tells him that they need him for the baby.
Glimpses of the preview have me thinking that Glen and Maggie are going to be in Dale's RV doing the nasty when it all goes down tonight.