If the Horde are going to enact "Scorched Earth Policies", which hasn't been their modus operandi and there's been no indication of outside of the Battle for Lordaeron this expansion, then fine. But I'm not convinced.
At least with Dark Shore a complete loss, it would allow for what remains of the Night Elves to be focused elsewhere and an actual part of the overwhelming Alliance victories in Tides of War.
Unless of course, "Scorched Earth Policies" means the extinction of the Kal'dorei. In the event that such things are inexplicably, inextricably linked, then we had a good run.
The purple people population of Stormwind will just have to rapidly evolve into some other kind of dorei variant.