The rumors and speculation are true, according to the most recent World of Warcraft live Q&A. Ion Hazzikostas revealed that both Mag’har and Kul Tiran Humans are on the list of allied races planned for Battle for Azeroth, in addition to Dark Iron Dwarves and Zandalari Trolls. If you feel like your old non-allied race is being left out in the cold, not to worry; while older races won’t be getting heritage armor per se, the developers do want to do something cool for veterans of the core races.
The discussion also ranged to Artifact weapons, which will still be usable at the beginning of the expansion; you won’t have all of the traits associated with it, but it will still be a good and usable weapon. It will sting to not have access to the old traits, but the design position is that it’s necessary for the longer term in the game. There’s also confirmation that crafting will now be split up by expansion rather than in an ever-ascending number, so you’ll have classic Blacksmithing, Northrend Blacksmithing, Outland Blacksmithing, and so forth. While it’s short on hard details at the moment, it’s enough of a nod to spur speculation as the expansion continues on in testing.