Sorry Valentine91 but as a Chris fan and very much not a Jill fan I have to disagree with some of your points. I agree that Chris is overused and needs a break, and I have nothing against Jill being in the next one, but I have to point out some of your flawed logic. You used Revelations to strengthen the argument that Chris was used too much but then refused to use it to incriminate Jill of the same crime. You also said that Chris's personality was incredibly flat (not disagreeing there) and that Jill would be a better candidate, but the fact is, Jill is just as flat as Chris is. They're both really static characters who are focused on getting the job done and not much else.
Other than that, I'd say Leon is a no. Ada won't go anywhere without her boy toy so I guess I don't want her in it just because I don't want Leon. I would hate for Capcom to use Claire's presence in a side game as an excuse to ditch her in the main games. She deserves more, and with a bigger budget maybe they won't screw up her face. I don't want Jake but he's pretty much inevitable. If (when?) he does show up, I hope Sherry's there as well because she was the best part about his campaign. Don't use new characters just to throw them away, though I'd actually prefer new characters to the old ones as long as Capcom is willing to actually keep them (seriously am I the only one who doesn't care what happened to Billy, Carlos, etc.?). My last request, please continue to make Mercenaries awesome because it is my favorite part of 5 and 6 by far and greatly increases the game's lifespan, and maybe they can put Chris in even though he better not be in the campaign, because seriously I can't get enough of him. It's a sickness. *hangs head in shame*