Originally Posted by Brain Damage
The thing is Fassbender, Hoult, and Lawrence have all become quite a lot bigger names since First Class. Fassbender had Prometheus (basically the only thing everyone could agree worked in that film), Hoult had Warm Bodies (which did modest, but was very popular amongst the tweens) and Lawrence has an Oscar and the Hunger Games. The only one who seems to be staying under the radar is McAvoy, and he was arguably the biggest name going in.
So, I don't buy that they couldn't have pushed a successful sequel on their own. But yes, undoubtedly Jackman and Berry will be increasing ticket sales.
It doesn't matter since the general audience are still more familiar with the original cast portraying these X-Men characters than McAvoy, Fassbender, Hoult and Lawrence. Also, Hugh Jackman was nominated for Oscars this year and will headline his own movie, Halle Berry is still a favorite of the tabloids and the movie that she headlined this year did well, Ellen Page had Inception/Oscars nomination in the past, Anna Paquin still has True Blood. And it doesn't matter if Shawn/Daniel aren't big stars since they weren't big stars before. Then if they include Patrick Stewart, Ian McKellen and James Marsden in the 8th X-Men film, that will be a plus.
And yes, they could push a successful sequel on their own than the cast of First Class cast. They already did that before with X2 and X3. Hugh Jackman already headlined his own Wolverine movie before (and that did well better than First Class) and he will headline another Wolverine movie this year. So who's to say that they can do a X-Men movie on their own.
And don't forget they always include new cast members in every X-Me movie. They might ditch First Class' core 4 to someone bigger.