only the future can be changed one thing that marvel has stuck with is any tampering with the past will only create alternate realities the main (616) timeline will be untouched so bring the original team to the present will not disrupt the present it will when the original 5 go back cause them to grow up in an alternate reality & no effects ( SAVE MAYBE JEAN STAYING IN THE PRESENT) will happen towards the 616 reality!!!!!!
Exactly, all it did was create a "What if? The Orginal X-men dissapeared (forever or a short time) into an alternate timeline?" alternate reality. That's the new fad of how to bring people back to life. Killed someone? Bring them from AOA universe or wherever.