The basic question should be, How far does French neutrality go? As is clear from modern times, you can supply arms to a revolutionary movement yet still remain neutral. In the case of the AWI, the French supplied arms and advisers to the Americans before they intervened militarily. The result was the American victory at Saratoga, which became the real hinge of the war on the American continent.
Let us assume this American victory, but that the French neither landed troops nor deployed any naval forces. The situation at Yorktown would still have arisen. However, with Washington unable to break into the British lines and Cornwallis getting unlimited supplies by sea, stalemate would set in.
At that stage the last serious British army in the that part of the world would be locked up in Yorktown and the British government had very few troops to send across the Atlantic. In view of the sympathy held for the Americans by large sections of the English Parliament, population and indeed in the Royal Navy, a deal would have to be worked out.
In fact I believe certain deals had already been suggested to Congress by British intermediaries more or less throughout the war, but had been refused by Congress itself, who were afraid they would be treated as traitors, i.e. hanged. Obviously after the above version of Yorktown, hanging would be off the table.
However, if the French had not supplied arms and the British had won Saratoga, the Brit government may have felt they were on a roll and proceeded with the suppression of the Continental Army. This would not solve the problem.
There were about three million people in the Colonies and they would still have to be administered and policed. The British Army in America before AWI numbered about 10,000. Many more would have been needed because of the bad feeling caused by the war and the British Exchequer had been depleted by the Seven Years War.
Let me leave this with a picture of a country with a weakened currency deploying large numbers of troops in another country where large numbers of the population don't like them and there is an active guerilla movement. Modern parallel, what?