I used to think of it as a "continent" made of zones from different eras.
But now with all this world revamp talk, I wonder if it wouldn't be easier to have the Infinite Dragonflight assault different zones in each patch, trying to mess with the most important events of each.
That way they would have an excuse to revamp the present version of that zone, while also showing a past version of it. Which would make for a lot of variety, as you could have a patch with pre-Sundering Azshara and another in Second War Blackrock Mountain.
It could be messy if the writing isn't good (and that's almost guaranteed nowadays...), but we would get a massive amount of lore from it.
The basic concept wasn't too bad. It's more or less the only feasibly kind of time travel. But once they got smug and started talking about AU Draenor being "the only stable" AU, and the Burning Legion being somehow one entity shared across all universes, it got really, really bad. They also rushed the Iron Horde and Grom's "redemption arc".