Dwayne 'The Rock' Johnson should definitley do Star Trek again, he would be a good Klingon!
I am being serious, Star Trek helped to start his acting career and hes done very well for himself since. GI:Joe and Fast & Furious have certainly benefited from his presence, and he is recognisable worldwide!
Mila Kunis is a big Trekkie and would certainly be in the next movie. If she is free!
Tom Hanks is still a big star and would make a good Starfleet admiral (Pike Replacement)!