Except that they really haven't. Iceman came out as a gay teen and began dating this annoying Inhuman kid. Angel went all cosmic and gained some fiery wings. Jean went off on her own for a bit. And Cyclops just moaned a lot.
But Beast kept on working on solving the riddle about why they couldn't travel back in time again. He eventually began experimenting with magic and finally succeeded in traveling back in time. He even told young Cyclops about it, but never got to tell him what he found.
The current ALL NEW X-MEN series wrapped up this week with issue #19 and Marvel Comics finally decided to revisit that discussion and explain why the All New X-Men cannot return home.
In this issue, Beast gathers the original five X-Men together and pulls out his magic time-traveling mask. Before anyone knows what's happening, they're back at Xavier's School for Gifted Youngsters on the very day that they left. Everyone is pissed that Beast yanked them back in time, except for Cyclops who never really fit in our present.
Then Beast shows them what's up: There's another group of X-Men fighting crime at Xavier's School -- living their lives like nothing ever happened to them!
In other words, the All New X-Men are from some alternate past timeline and have no idea how to return to their world. Or time corrected itself and created temporal duplicates of the X-Men. Or something. Either way, this isn't the All New X-Men's timeline and they need to return to the world where they've lived for the past few years.
This actually contradicts what Marvel Comics had been doing with time travel for a while. There was a story where young Cyclops was killed and the adult Cyclops disappeared because he'd never existed. Fortunately, the younger Scott was brought back from the dead so the older Scott came back.
But I've been reading Marvel Comics comic books since the 1980s. Most of that time, there was no plucking people from our direct timelines. If you went back in time, you automatically created a divergent timeline because you've automatically changed the past by being there. So this new revelation about the All New X-Men actually appears to return things to the status quo.
And I'm happy about that.