We're looking too deep...too old. Remember academy kids...late teens early twenties. AFAIK no one that has been discussed fits that description. Who ever plays Kirk, Spock, Mitchell, Marcus, Finnigan. Is going to probably be someone we've never seen before, or we have seen them, but as a child actor years ago.
There is still plenty of other people that older actors can play. Bob Wesley? Garth of Izar? Nogura? Pike? April?