Look, we know they want us all playing together. We also know that they don't want the new player to "choose which half of the community to hit you with fantasy racism" upon arrival in the game. If or whenever they ever lift faction restrictions, yes, it's going to be a tribalistic mess until the feature is trivialized. Whether they do it now or later, there will be a period where LFX is full of "dirty [faction]" vote kicks and insults, so either say NO when asked pointedly (good on Scott Johnson BTW for point blank asking: "this isn't happening, right?") or tear the bandaid off.
I for one don't see them ever doing it unless they can completely "community proof" raids and dungeon access with some kind of NPC party, but in the meantime, "never say never" just feels wrong to say. They created this toxic tribalism, and now it's their major hurtle to overcome. It's got nothing to do with "the soul of the game" and everything to do with "welcome to world warcraft... half the community hates you by the way, look forward to them in chat!"