Well I read in one of Marie Antoinette's biographies that there was an incident a few weeks prior to the revolution in which Louis suffered a fall that he was lucky to have walked away from unscathed.
What if he had broken his neck and died? Leaving his young son as King and the nation in need of a regency? There's a POD that could mitigate the revolution into a crisis of more manageable proportions.
Hm, how likely would Marie Antoinette be to try and escape the country without Louis, as they both did in OTL in June 1791? My impression is that Louis XVI was by far the stronger will in the pair, and Marie Antoinette alone could well be too cautious to run.
No flight of the royals would be a big change to the revolution.
Getting back to the larger question, how about I break it down a bit?
How likely do people think it was that the Estates General were called in 1789?
My impression is that this depends very much on when de Calonne decides that he needs to stop paying for everything with borrowed money - if he bites the bullet earlier or later depending very much on how his internal debate goes. When de Calonne decides he needs to raise more revenue, given the character of the King, the Estates General meeting is pretty much inevitable.
Once the Estates General is called, how likely is it to melt down into chaos?
My impression is that as long as Louis XVI is still king and Necker is still alive, things are very likely to melt down, though the exact events of the melt-down could be very different.
How likely is the chaos to get ideological (that is, for rioters to start thinking about "liberte egalite et fraternite")?
My impression is that these were ideas whose time has come, and that any large disturbance was likely to accumulate ideological trappings - witness the parallels in Leige, Belgium, Poland and the United States during their revolutions in the same period. So a big melt-down in public order in France is, in my view, very likely to gain a republican or constitutionalist rational+liberal+secular ideology.
How likely is an alt-French Revolution to spawn an alt-French Revolutionary war?
Personally, I am of two minds on this. Firstly, the exact progression from French Revolution to French Revolutionary war seems very vulnerable to being derailed by a different international situation, or a different political situation within France. For example, with an earlier French Revolution, or a world where Mirabeu simply lives longer, I could well see the French peace camp winning the debate. Or, for example, in a world where Prussia and Austria do not experience a rapprochement, we may see no Reichenbach Treaty, and thus no casus belli for the French war hawks.
But then, during this period, there were regular major wars, and France was about due to get into another major war with Britain. So even if the doves in France win, we may well see a new Franco-British war in a year or two of the alt-Revolution and then the ideologies will work their alchemy turning this Franco-British war into a Revolutionary War (tm).
fasquardon