I've put a lot of thought into this since reading the leader short stories.
1) Garrosh needs to do some SERIOUS PR work just amongst the Horde. I'm not saying stop the war, but reach out to make amends with the racial leaders.
2) Gallywix should probably just be IN the game somewhere. Or get assassinated so someone else can take his place (Boss Mida! Here here!)
3) Lor'themar needs to grow a pair. I mean, I know he's in a tough position but he needs to start making the most of his position in the Horde, working with the Horde diplomatically to help his own people instead of being bullied by Sylvanas and trying to beg forgiveness from the High Elves to get out of it. I mean, for serious, the Blood Elf mages all have portals to Orgrimmar. It is not hard to get the other leaders of the Horde to work WITH him.
4) Sylvanas..... is crazy. I don't know how to "fix" her, but I think it's possible she may just need to be killed off.
5) Baine is busy living under his father's shadow and probably conflicted by his friendship with Anduin and the war with the Alliance. He needs to figure out what he wants to do -- pacifism is not an option any longer.
6) Vol'jin has to decide the Horde is worth still contributing to. I don't know what will lead to this realization, but once he realizes Garrosh is NOT the Horde even though he's the Warchief and recommits himself wholly to the Horde, I think he'll improve a lot.
7) Varian's growing as a father, and I think he's actually one of the best handled characters at the moment. I see him as taking the lessons he's learned as a father and applying them to his leadership of Stormwind.
8) Genn Greymane needs to do SOMETHING. He should be helping reclaim Gilneas, I think.
9) Gelbin Mekkatorque has, as far as I can tell from the short story, finally reclaimed Gnomer. So now he needs to be recommiting to the Alliance. I mean, part of the idea of reclaiming Gnomer was to have access of all those brilliant inventions again, right? So let's see them.
10) We know from the short story why Velen and the Draenei were distanced from the rest of the Alliance. Now that Anduin has sort of awakened Velen to his responsibilities, let's see him *actively* preparing for this Army of Light he's so obsessed with.
11) Tyrande was SOOOOO BAMF in Warcraft III. And since then, she has not been at all. I want to see Tyrande take an active leadership role, I want to see the heroic Tyrande not the "I'm waiting for Malfurion" Tyrande.
Speaking of Malfurion.... can he go back to sleep yet? I just find him dull. Maybe it's just me.
13) The Council of Three Hammers just needs to find a way to restore Magni. I miss him and the only interest I have in the Council is to see how much in-fighting they do. After the whole thing with Moira, they seem to be getting along too well and not only do I find that unrealistic, it's also really dull.