I suspect he may yet, if only so that the Emperor might make a living example of him, to demonstrate the futility of such actions against he who leads our Empire. To make sure that any future attempts are made only by the worthy, and not merely the ambitious. He does, after all, have an obligation to ensure that his replacement will not simply plunge the Empire into a brutal civil war as everyone else seeks to depose his successor. He who sits on the Emperor's throne must be able to hold it, and only someone of both power and vision will achieve that.
And, if they do not, I'll see to it that they don't live long enough to enjoy their prize.