No Khan for me. It's been done, and it was done well in my opinion.
The last film tried to make Trek a whole new universe with fresh ideas, so use that to the full potential rather than re-imagine ideas that have come before. Such a film would only draw comparisons with Space Seed and TWOK, and I'd rather not see that and all the arguments amongst fans that go with it. I'd like the film to be viewed in its own right as a reboot/re-imagining, whatever you want to call it set in its own independent corner of the Star Trek world.
Some of the biggest complaints about the TNG-ENT era were that the franchise was lacking originality by the end and treading over the same ground again. Nemesis, despite some of its other flaws, took a pretty harsh beating for its similarity to some of TWOK's aspects. So avoid this totally and give us something completely new.