Ok here are my thoughts.
So I saw the alliance ending first and WTF Voljin is there saying "I SPEAK FOR DA HORDE" With thrall behind him starting at Varian. Varian and the alliance come off really well in the ending all high and might and can finish this if they so choose.
The horde ending then shows Voljin saying we need our true warchief (clearly saying thrall) Thrall muses and says Voljin should be the one to lead the horde. After seeing this I did not feel so bad about the change in command. The other horde leaders bowing and Voljin showing real humility saying he does not deserve it but will do his best.
As for Garry, his head dropping low after realizing he will NOT be killed right away. You can see it in his face he looks terrified. He knows he is in disgrace now and for him thats worse than being dead.
So on the one hand I was saddened not to see Thrall in charge but on the other I kinda like this new direction it gives me lots of new questions Does Thrall now lead the Orcs and focusing purely on them so he can ensure they never go down this dark path again while leading the horde to a trusted friend who he knows will do his best to ensure the horde stays true?
Garry goes on trial this could be a patch in 5.5 where the vale is being slowly restored (new dailies/phasing) we have his trial where we present evidence, you could involve your player character and show the others what Garry has done and then at the end of it we see what fate aways Garry and if he has anything to say for him self. We can help with the restoration of the vale.
We could also see in this patch Gilneas being reclaim the Forsaken would most likely have left the place under orders from the new warchief and the alliance can begin cleanup operations of the area, possibly a small daily quest line or something?
Lots of potential. As for the horde we could get a quest line where we go around fixing things in Orgrimmar after the siege in 5.5 so both sides get to experience post war effects.