User blog comment:FairyRaven/Fairy Tail Chapter 465: 400 Years, Review and Commentary/@comment-7418318-20151208023259/@comment-7418318-20151209154157

Maybe the workings of the Eclipse Gate are the key here.

We know that if the Gate is destroyed, the time travellers are pulled back into their own time.

So that leaves us with two possibilities:
 * 1) The Gate is still around and intact.
 * 2) Layla and/or Anna did something to sever the connection that the Orphans and Dragons had to their own time. Maybe it was this severing that killed Layla. But even with this route the Gate might still be around and might possibly be used in future chapters.

I just hope we'll get some more answers and aren't left to figure things out by ourselves.