How would you make a major faction change work in WoW without breaking the leveling experience?

More and more lately, World of Warcraft seems to be headed for some sort of major change in factions as we know them. Even ignoring the general complaints from some — but not all — players that the faction conflict is outdated, the game itself is dropping hints left and right. The most recent of those hints came from the newly released cinematic players will see after they finish the later steps in the War Campaign. Without spoiling it too much, there’s a very important conversation toward the end of the cinematic that feels like it’s screaming, “WE DON’T NEED FACTIONS ANYMORE!” Seriously, it’s either a major misdirect or some very heavy foreshadowing.

But every time the conversation of no factions — or a third faction, for that matter — comes up, I can’t figure out a good way to make it work without having another Cataclysm-style revamp of everything that exists in the game now. Right now, a large portion of the 1 through 60 experience is built around the faction conflict. Burning Crusade and Wrath of the Lich King are less on that side, but then Cataclysm and Mists of Pandaria content pick it right back up. And, of course, Battle for Azeroth is built around it more than any other expansion. The faction conflict is built into the DNA of the game.

The closest I’ve come to a “solution” would be making the player level to 120 (or whatever the equivalent after a potential level squish would be), experience the full story of BFA, and then… let them pick a new faction? Go on faction-less? Defect to a third faction? Even my best approach isn’t perfect. And let’s say Blizzard did do something where you only experienced the faction shake-up after a certain level — what happens to characters who are boosted?

It’s pretty much tradition at this point that you can boost to the latest content, so that would mean new players would be in a faction-less (or, again, three-faction) world with low-level quests still tied to the old faction boundaries. Would they just not be able to do them? Like I said, I can never get over this hurdle when trying to come up with a wholly different World of Warcraft. But maybe you can! How would you do it?