I've got a theory about Khan/Montalban casting probs, and would love to see if anyone agrees. The essence of Khan is intelligence, erudition, masculinity, charm and arrogance (his fatal flaw). Like many movie stars of his generation (Lancaster, Peck, Mitchum). Montalban had those qualities (or at least knew how to play them), but few do today . How many present day actors do, or can convey convincingly? (all those Pattinson 'pretty boys' *aargh*). Clooney comes close overall, but no. Rourke & Cage - admire, but just a bit too 'damaged' and leftfield. I could almost imagine producers looking for a Brit or foreign actor: like Rickman as Hans Gruber (c'mon, wasn't he a revelation and a great villain?). Or here's a really wildcard and JJ connection: Cruise...(bit short, but has a lot of the other qualities...lol).
Or... how about Patrick Stewart? Wouldn't that be wild....