The belfs that were "everywhere" were not affiliated with the horde
Varian coming back is more significant than the displacement of one horde leader.
Jaina in no way is a supporter of the horde. In the Shattering novel, she says she will march at the side of the king if they attack orgrimmar.
What druid....
Someone who formed the horde on azeroth wouldn't be so quick to abandon it.