I think there are a few people who need reminding Lordaeron is the nation, Capital City is the ruins of what Undercity now is.
With that in mind, its highly plausible without "hurting" the Horde, it can even lead to some truly good story telling. With Stratholme reclaimed that could always turn into an Alliance hub, Tyr's hand could be re-developed or Stromgarde too, maybe even Alterac. Or we could actually build something out of The Hinterlands base already present, or even reclaim Gilneas Many possibilities, but I can see a future for the Alliance to reclaim a Stronghold in Lordaeron, again, without hurting the horde and actually creating some story depth and continuation.
Calia Menethil, the heir to Lordaeron is still missing, so she could make a return.