Way I envision it, you’d be able to keep all your stuff, all the races would still exist (except void elves are high elves with some extra customization, and the Alliance gets (Shen’dralar) “nightborne” (horde can still keep Suramar)).
You’d have to play around with the races a bit. Maybe establish that there were always a few zandalari and vulpera working for the Horde (and then invite them fully into the horde as the story develops).
Ideally, we’d be starting in a revamped version of vanilla and TBC, just so Blood Elves and Draenei can still be in the mix, and COMPLETELY REFRAME the Illidari back to what they were in Warcraft 3 (lovable anti-villains) instead of turning them into generic raid bosses and edgy Jesus metaphors. Keep Kael’thas king, remove the problematic “crush” he had on teenage Jaina (I swear they only added that into the lore to properly villainize him for TBC) and maintain his friendship with Illidan, Akama, and Vashj.
From there, maintain the ORIGINAL lore on magic, the cosmology, and how the setting fundamentally works, and EVOLVE IT FROM THERE rather than RETCONNING EVERYTHING.
I also have plans on how the Eastern Horde (including Sylvanas, Varimathras, the Revantusk, and Kael) SHOULD have developed. I talked about that in another post:
I could go on, but in short: yes players could keep their stuff in this scenario. Story-wise, just say its stuff from an alternate reality.