Certainly a redo. There has been so much harm to aspects of the story that a time skip doesn’t resolve them, they still happened.
I’d write in a reasonable time skip or space between expansions cause back to back to back world ending threats gets… boring. Just a couple extra years, nothing crazy. The PC stays grounded too, no continuity between 3 or 4 over arching expansions to where everyone knows you. Maybe a mention here or there but again, nothing crazy. (General, Order Hall, Hero of the Horde/Alliance, of Azeroth…)
I’d probably rewrite a lot of BC and tie loose stories together. In a perfect world we’d still have Kael’thas in some capacity. Tempest Keep can still happen as is, but the end result brings Kael back into the fold either by his admission of his own double crossing of the Legion or whatever else you can put in there. Really anything that saves killing off such an iconic character as raid fodder. Illidan can probably stay as is? Horde bias, I really don’t care too much for him and feel he got a decent story in Legion.
BfA would probably the next most redone expansion too. Push it back a whole expansion as we try and stabilize the world from old gods and the like, the entire time however trust runs thin as factions fight each other, either under Old God influence unbeknown to the other or for outright opportunist bloodshed.
Alliance attacks first, we get our nice For the Horde Sylvannas, Proudfang, big Tauren boi. Undercity stands, barely, Teldrassil is too far out to siege, Ashenvale is getting clear cut but not without resistance, and the war wages on until more level, superstitious, or spiritual heads start to raise concern about the souls of the dead and bam, Shadowlands.
A lot of other more minor things too, but those are probably the more egregious examples. 13 month content drought in MoP and WoD needs to be addressed too.