So, with Alleria and Turalyon coming back and their story being told in some detail, I wonder if it sets the stage for a kind of reboot. Like this:
Background: Alleria and Turalyon are thrown into the Twisting Nether as our Draenor becomes Outland. Things happen (see the story on Blizz's site) and they come back to us after 1000 years of their time but only a few decades of ours.
Effect
That's the perfect mechanism to have a jump forward in time... just reverse the ratio. Have us do an off world/in the Nether expansion (not the next one, perhaps the one after). For us, it's a year or two of subjective time. We come back... and for Azeroth it's been decades/a couple of centuries.
That would allow them to present us with new threats, a changed world, etc and fit in without it feeling silly.
WILL they do this? Probably not. What would the threat(s) be? No idea. I think having us defeat things as large and powerful as the Void Lords is bad fiction since it makes us far too powerful and every other possible threat puny ("Oh look a new Lich King. How cute. We just killed off the most powerful representatives of the Shadow... [flick]... oh look a dead Lich King..."). But if they want to do a reset or a time jump, they've set the stage with some background that makes it plausible.