Well things are going to get messy back home. IIRC when General Malet tried to launch his coup by faking letters that Napoleon had been killed in Russia and reinstating the Republic one of the striking things was how quickly and easily everyone discounted his son, so I doubt that the succession is going to happen like Napoleon would of wanted. Expect to see his generals maneuvering for position to either claim leadership themselves or to act as 'regent' for Napoleon II. I want to say that at this stage that France is pretty much doomed since they now have nearly all of Europe arrayed against them. If Napoleone, the personification of what was evil to the allies about France, is dead though could the French possible pull back within their own borders whilst trying to negotiate an armistice and peace? Or would the Allies merely scent victory and keep up the skker?
One option that might be amusing would be for Malet to launch his coup (he believes) falsely claiming that Napoleon had died and the Republic restored and put down as in our timeline only for it to be actually true and the news to arrive a short while afterwards.

No-one would know what was going on. First he's dead, then he's alive, then he's dead again, maybe he might turn up alive? "It's Empire!" "No, vive la Republic!" "The Emperor lives, crush the revolters!" "Uh, yeah, about that whole living thing..."