User blog comment:ADour/The MARVEL UNIVERSE is ENDING!/@comment-2204174-20150406181652/@comment-4651179-20150406204628

It has already been confirmed that's not the case:

"No, we're not segregating the X-Men into their own universe," [Alonso] added. "The X-Men are an integral part of the Marvel Universe. They play a big role in 'Secret Wars,' and those mutants that survive the event will be crucial building blocks for the Marvel Universe moving forward." (sauce)