I think the most likely to return are Kelly Kelly, Eve, Maryse, Kharma. Any of those. But again, it depends if they want to drop what they're currently doing outside of wrestling and come back, and when you think about that, then it's perhaps a long shot to think about them. As far as those 4 go, I think Kharma is the only one who's not doing anything outside wrestling right now. K2 is modeling, Eve is acting and hasn't Maryse started her own jewelry brand or something?
I think a full time return for Trish or Lita are unlikely. Part time though? Who knows.
You can rule out McCool due to the fact that she's raising a family with Taker (didn't they have a baby recently?). And beth isn't dating Punk any more man, as Wade says, she's dating Edge now and I'm sure she's happy taking a break to be with him for a while.
In short, I'm skeptical whether or not any divas will return. I think WWE are better off concentrating on building their NXT divas to be the next crop of stars.