Hear me out:
Night Elves are my favourite race, so losing Teldrassil was pretty gutting. But for most of their history, during the Long Watch, Night Elves seem to have lived in the forests. Returning to that again wouldn’t be a problem as long as they kept their lands. They already have a fully restored Hyjal and World Tree, as well as part of Feralas. And considering they won the Battle of Darkshore, I don’t see any problems for them getting back most of Ashenvale. If they restored Felwood like the druids did for Western Plaguelands, they’d be sitting pretty land-wise. Not to mention they could probably create a new Darnassus if they wanted, since they did so after the Third War.
As for the Forsaken, they’re far more adaptable than other races. They could take the Cleft of Shadows in Orgrimmar. If the gnomes could do it in Ironforge, why can’t they? Plus, even if they retook Undercity and Tirisfal Glades (Lordaeron ruins could remain blighted as a tragic monument but the underground city might be recoverable), I don’t see anyone else having a problem. Forsaken didn’t really need Hillsbrad, Gilneas or the Plaguelands anyway - they just wanted it.
So them not getting their cities back or even new cities, as long as they get some racial districts to call a ‘capital’ and proper lands, wouldn’t be bad.