Thanks Alex, all options a possibility, but I'm not quite clear on whether your premise has Bonaparte alive and in power as First Consul when Kléber returns, or whether he's dead and burried in Egypt?
If Bonaparte is in power, then the above scenarios can tally, except for #2 - It is unlikely Kléber's troops would abandon him entirely as the majority of them still hold a grudge against Bonaparte for abandoning them (desertion in the face of the enemy, plain and simple, in the minds of most, with the exception of some die-hard Bonapartists like Menou). The Klébertist faction was quite strong. He would certainly make the case of Bonaparte's desertion with his fellow generals and members of the political class that are republican-minded and I expect more than just Jourdan would rally to him. Also, Kléber, considering his experience in the Vendée wars, is unlikely to march on Paris. He sure learnt a thing or two about civil and guerilla warfare, experience lacking on Bonaparte's curriculum I believe ... Can we consider another civil war as a scenario?
If Bonaparte's bones are bleaching in the desert sun, then I believe Kléber would have even more of a chance of rallying Republicans around him upon his return (don't underestimate his connections in republican and masonic circles). As he states clearly in his personal notes written in Egypt, his ultimate ideal is to install a presidential democracy, styled on America, his ideal statesman being George Washington. In fact, Kléber only came out of retirement to join the Egyptian Expedition to "check Bonaparte's metal" and see if he would be the hoped for French Washington. Big disappointment ... so, if not Bonaparte, who could've been the French Washington Kléber and his fellow republicans could've championed?