I think the leak is real, but not to be taken at face value. I think there's two things wrong with it.
1. Garrosh, not Grommash. The leaker hadn't played since Cata, so had no idea who Garrosh is. Upon being told Garrosh is an antagonist, he assumed Grom was getting a rename. Quick search would bring up Grom Cycles, and the "legal issues" were explained.
Garrosh wont be the final boss, but he wil bs one od the Warlords.
2. Time walking was mistranslated into time traveling. Timewalking being a feature from the front page thatd let you scale your level for old instamces.
Excuse errors, im on my tablet.