When will it be lost, because the longer the war goes on for the longer the discontent. For instance , I think if the British win the Battle of Bunker Hill with minimal human cost, then thats really the last chance. Lord North was conciliatory, but the Americans might not be. If you plan a war won in the time of Cornwallis' campaigns in the south, then you have a sort of Ireland situation for the next seventy, eighty years- the 13 original colonies are constantly rebellious and pushing the envelope all the time. After that such discontent might be diluted by new immigrants arriving from Europe (again, no reason to believe why this should be really different; I asked Niall Ferguson in an e-mail on this (surprising, non?) and he agreed).
With regards to France. Before, France was doing well in getting rid of the Seven Years War debt, and I believe without the ARW France might survive in its current, absolutist state. Of course, Louis is a bit of an Anglophobe since France lost sooo much in the Seven Years War- he could provoke war later on with the UK anyway (in my TL he does). He could also expand on France's navy (something with he loved), or look upon his country and reform. I have a rough idea of Louis (depends on his personality really, but there is wiggle room) looking upon a reformed British America (in the collaborative TL in working on) and decides to reform the legal system. Louis is thus seen as the guarantor of French liberty against the perfidious nobles, and guarantor of law and order. Some of the discontent of the French lower classes and bourgeoisie could filter away- until 1791 Louis was generally popular as a person, unlike his ministers and his wife. Helpful?
You also seem to have worries on the British colonial expansion. The antipodes could definetely look different- Australia and New Zealand could have gone French very easily (a French warship was spotted scouting off Botany Bay once). India would probably still be British, given the real French presence was shrunk in the Seven Years War. Africa is hard- it all depends on what the butterflies are....