First off, let me say that while an expansion using elements of time/dimensions travel would be cool, a full fledged expansion about it would be absurd. It would not only confuse most players, it would create giant gaping plot holes in the games story (WotA and Thrall novel show how bad Blizzard is at executing time travel and keeping it in game). Anyways, I noticed a lot of people jumping on the bandwagon because of two threads claiming to be real (never been done before am I right). Anyways, I could be wrong, but here is why I honestly think, whether or not WoD is real, the plot being held heavily focused on time travel is most likely mere speculation.
-Scrolls of Lore posted about Warlords of Draenor before the thread on MMO-C popped up. So the fellow with one post didn't necessarily have inside information.
-Blizzard received flack for two expansions in a row being Horde-heavy. Now realistically, would the next expansion deal with the players helping the Old Horde after all of this criticisim. It would be a huge 180 on how they said next expansion would be Alliance-heavy.
-Those who never believed The Dark Below always said it was fake because the trademark wasn't legitimately filed or something like that. Now, its claimed to be the name of Titan (uhm, why?), a game we know NOTHING about, and people are happy believing it is real.
-I doubt there would be two Hellscreams as Final Bosses two expansions in a row, both due to the faction bias that will be claimed and the repetition of having two expansions killing Orcs.
-Lastly, and perhaps most importantly and I cannot stress enough, WHY THE FUCK WOULD THERE BE LEGAL ISSUES NOT ALLOWING BLIZZARD TO CALL HIM GROM. In WoW, he is almost never called Grommash, only Grom, now all of a sudden it's illegal for Blizzard, the company the created him, to refer to him as such. Makes absolutely no sense.
Warlods of Draenor may just in fact be real, and time travel may play a role in it. But to accept these claims that it is going to be a time travel expansion, Horde focused (again), and then involve events that have no impact on the present story (changing shit it the past doesn't affect the present you came from, it creates another timeline), make these claims EXTREMELY unlikely.