Q'Anilia
Exiled Master Jedi
Risks are that Ganondorf would probably hope to outwit Kil'Jaeden. Expect the end of their alliance and beat him to the chase, after Kil'Jaeden has served his purpose. That alone would end up a clash between wits, but because both pride themselves in their intelligence, it is hard to see how it would end 😛
Ganondorf having ten years, I think he would decide to leave the Burning Legion out of this, not that they would be for long. The Old Gods would also like a part of this act. In the end, Ganondorf by attacking Azeroth would give an opening to so many threats. He will have started Deathwing's quest, will have given the Old Gods an opening and Kil'Jaeden could track down new doorways into Azeroth, doors closed before Ganondorf stepped in. He will end up destroyed by Azeroth's enemies.
Truth be told, personalities taken in consideration, it is impossible to have the outcome of this foretold. Too many parts of the equation that can not be excluded.
The only thing that would have a definite ending, would be if Ganondorf has a habit of playing with time and ended up meddling with Nozdormu's realm.