The new emporer is Solus' Grandson. His younger son (Being the deceased older son's brother) and grandson (Son of the Elder Sibbling) were the two side in the War of Succetion. And the Grandson won Prusumably by killing his uncle since that's kind of how it works. It also said none were left who COULD oppose him rather than would. So it may be that any non-supporters he has simply won't rebel due to the futility of it.