From what I've heard of the movie, it will be the old characters (Kirk and Spock) but younger. Please, no Queen Latifah as Uhura. Maybe Beyonce Knowles would be OK -- yeah, Uhura could sing.... Craig Kilbourne as Scotty?
Considering that Shatner was 35 when be began playing Kirk, and Affleck right now is 33, that's not much younger.