It's not so much that they aren't seen as dependable (they aren't, but still), but more that after the battle at the end of Jade Forest the Horde survivors got spirited up to Binan Village and never backtracked to gather up more Hozen. You come across Horde-aligned Hozen later on, but not in huge numbers. There's one in particular who operates a kite stand in Domination Point and acts as a sort of Mr Exposition in the Dominance Offensive questline. Plus you can always go back to Grookin Hill and it's chock full of them, got a Horde flight path and inn there.
On the original topic, Outland is probably not going to get an actual revamp. What I think is considerably more likely is that one or all of the remaining defunct
dimensional gateways in Outland - the ones that tore the planet apart - are opened and stabilized, leading to a new Legion planet to explore. To quote Metzen,