While I wouldn't go that far, I will say I will be very disappointed in the writers if it ends up being Khan, whether Space Seed or Wrath of, doesn't matter. Next we'll hear Trek 13 will feature Trelane, 14 will feature the Tribbles, and the rest of the films will feature Harry Mudd.
New villains, people - not rehashes.
Having said all that, if they do cast a new Khan whoever the pick should be a powerful, preferably Hispanic actor (the character isn't Hispanic, of course, but Montalban made such a mark that having, say, a Brit play the role just wouldn't feel right). Edward James Olmos actually comes immediately to mind, especially if this ends up being an older Khan. Banderas is too much a light-character actor - I like him a lot but I'd have trouble accepting the guy from Spy Kids and Puss n Boots as Khan. Bardem is still a possibility if the Bond film is wrapped in time.
Of course if everything I just said about the character being Hispanic is thrown out and the doors are open wide, then one name comes to mind: Ian McShane!

But ONLY if he plays Khan in full Al Swearingen mode, of course!
Alex