You're operating under the assumption that the Alliance has the upper hand here, that just because Garrosh is dead it means the Horde is dying on the ground like a writhing child. The Horde will still have the prescense of Sylvanas, Baine, Voljin, Gallywix(lolmaybe) and of course Ji Firepaw - I think they will be able to run the Alliance out of town and make the issue of them 'deciding if we are fit enough to rebuild without their supervision' a moot point.