Although possible, I do not believe that the emperors of Cantha were descended from the gods, possibly a hero. I believe the first emperor was called Kaineng, which the town was renamed after, and there is no mention of him being descended from a god, nor is there any mention of any emperor after him being descended from a god.
As for you believing Usoku did the right thing, how does forcing all non-humans out *or possibly killing them off* become a good thing? Forcing the Luxons and Kurzicks back into the Canthan Empire, yes that was good, but removing the non-humans out, not so much. Also, seeing how Usoku should be dead for GW2, I don't think there will be a story of Evil Empire/Emperor vs Good Rebels.