Kaaaaaahn!

J.J. Abrams talked Star Trek 2 to the MTV folks--Mainly about the notion of bringing in Kahn--Ricardo Montalban's infamous genetically engineered villian to the sequel.

The script is still being fleshed out by Alex Kurtzman, Roberto Orci and Damon Lindelof but JJ says:

"Now that we are in a parallel existence with what fans of the original series love so much, we could introduce any number of characters, settings, references and situations that the original series introduced," adding "Dealing with Khan would certainly be a challenge, but we had an equal challenge in finding our crew of the Enterprise."

If they use Kahn Casting has to be beyond perfect.. It can no doubt be done but it would still be very difficult.

Beyond that I really think it would be a mistake to remake any film or episode outright--The best approach in my opinion: Reference the classic timeline all you want a million times but wrap them around an original adventure...