Just wanted to comment on this and someone else might've and I missed it. As you mentioned we already knew from 5.1 after Martial Law was declared on Sen'jin village that the trolls hate Garrosh. Now we know that Baine feels the same and that he wants to get his men out of Orgrimmar first so that their blood isn't accidently shed. Lore'themar has hated Garrosh since at least 5.1 as well (perhaps even longer, just like Vol'jin himself has). Sylvanas we found out during Silverpine back in Cataclysm her thoughts on Garrosh especially after he ridiculed her and had his guards watch over her.
Now we have the Goblins, who will more than likely side with the rebellion as they might see them as the "highest bidder" in terms of supplies and success chance unless Garrosh can pull some strings or something. Since Gallywix is more than likely not to happy with Thrall from the Goblin starting area, but it's really hard to tell since we haven't seen much in term of Goblin Lore after the isle.
That leaves the orcs who will probably split 50/50 on who they side with. At Domination Point starting line we know that some of the orcs question Garrosh's actions and believe he has lost it. His main "right-hand" man that sits at the point issues the quest you get at every X rep level (Can't remember his name) is among one of the people who disagree with him.
Will definitely be interesting once the patch hits on test realm and more information is added.
Also, is there an option where I can attack the Alliance when they do the sea attack? lol -- You know like secretly take them out one by one while they are distracted =P