Your idea immediately reminded me of something I recently responded to Darhliana the other day:
Give me those sweet sweet reps right into my veins. Who you need killing? Did you know you can be exalted with the Bloodsail Buccaneers and the Steamwheedle Cartel at the same time? I’ve committed pirate genocide to the point of making Nathan Drake look like a saint.
Though, I do see one likely situation due to WoW’s older tech, which I discussed last night, actually:
Unfortunately I don’t really see it plausibly working for legacy content.
But, then again, maybe they could open it up, since, well, Allied Races make no sense going back and leveling through content that wouldn’t actually have been around for, so there’s plausible leeway to suspend disbelief for that. But they would probably have to wade through a lot of programming bugs it might cause.