Re: First Class 3 or X-Men 5?
They are setting up possible X-Force links. It's that simple. Plus most of the new mutants are plot devices for time travel and not major characters in the story it would appear.
I think this is Stewart and McKellan's last go around. The other OT actors have supporting roles and were on the set for a few weeks tops. Who doesn't need the exposure in Hollywood these days? Not like this project was beneath the likes of Anna and Halle. They need exposure and this is arguably the biggest film of the summer next year.
I'm 80% sure it's done after this. FC3 will be the stepping stone for the future.