Hmm, how are you going to get this fifth coaliton? IOTL pussian neede the destruction of the grand armee in russian to go back in, russian got invaded, so did spain. austria stayde out for a long time even after this. In this time line talyard is not in russian tellyin the tsar how weak france is, the army is not slovly bleed out in spain, and it wont be destroyde in russia. Metternich did not what to remove franche doimnas for a russian british one.
So the question stand, what can brittain doe? Its economy is suffering, riots and they have no whay to really hurt the french above finacing its enemys, non who are able to attack effectively.
I think there would be public and violent differences between members of the Imperial elite (Bonaparte family members and Marshals). As in a short civil war/coup before 1810. Tallyrand might even end up being forced out in the "Reform" of the Regency Council. Then he goes to Russia and provides his OTL role.
Russia publicly walks away from the Continental System, Spain is clearly waffling, and Austria doesn't feel that France is going to be have the same success now that Napoleon is gone. Spain publicly breaks with France after being given an ultimatum by the British threatening the end of its American empire. The French decide that they need to make a stand, and invade Spain. This invasion is met with a duel Anglo-Spanish force, commanded by Wellington, who beats back the French invasion.
Austria and Russia now declare war and send armies west. The Prussians sit on the fence, but after the defeat of another French army in Germany they join the Fifth Coalition along with other petty German Kings. The War of the Fifth Coalition lasts for two more years, and ends with Allied troops in France. The French war effort is marred by bickering between Marshals and Bonapartes, and the end of the war comes with a series of betrayals, as Marshals abandon the Emperor and swear alliegence to King Louis XVIII.