I don't think there would be much reason to making CVX2. Chris took out Wesker already, so as far as I'm concerned at least, it's only a matter of time before Umbrella dies. Wesker always felt like the rotten core of Umbrella, with the others- Birkin and the like, simple interested in the science of the virus rather than it's military components. Sherry may be a loose end, though to be honest the thought of what happened to her has never come up in my mind until just now, and even in this case I don't really care. Same with Steve and I really liked him lol.
One of the things that Resident Evil is good at (though I feel they faultered a bit with 4 and 5) is coming up with very different stories for each of their games, with contant shifting between main characters. CVX2 would be redundant. As far as characters making a comback... you never really know. I think we're do to see Claire again, in something other than Mercs 3D.