I mean....it is what it is. The vast majority of the actors in this show won't have stellar careers after "GOT" ends....same as "The Sopranos"....same as "Breaking Bad"....same as "The Wire".
"The Wire" probably has the best ratio of successful actors, though.
Fred.
Totally different shows. Most of GOT are "real" actors while Sopranos was half real half ex mobsters/steriotypical italian actors (paulie, bobby baccala, silvio, gay guy) and the wire had a lot of actual hood dudes like snoop and slim charles and underutilized/"new" talent (mike, omar, stringer, avon and wallace).
If anything the got actors are getting it earlier like arya and sansa part of xmen franchises and jon/jamie/dany already stars in feature films since joining show. Even robb had a leading role in the live action disney cinderell flick. Guys from sopranos and the wire aint getting roles like that (MOST anyway). Most the older actors were already established in film and theatre like tywin, cersei, lil finger, 3 eyed raven, stannis, etc.