But would the French hold on without the promise of US troops?[/COLOR]
IMO yes.
Like the german one ( general strikes in the armament industries ), the french crisis ( mutinies ) were not that about surendering to the foe, but about how the war was conducted.
The french troops didn't object to defending their country, just to having their lives thrown away for no reason in pointless offensives which got nowhere. Unlike Russian troops, they didn't desert and remained on their defensive positions, refusing orders to go on the attack.
OTL, this was dealt with with a lot of carrot ( change of commands and promise to wait for ' the americans and the tanks ' ) and a little of the stick ( IIRC, 57 mutineers were concemned to death for those mutinies, just a fraction of the total during WWI ).
The former can easily be changed in a promise to wait for the colonials and the tanks before going on the offensive again. The interesting part is the effects of introducing conscription in the french colonies will have on post war relationships there.
Bottom line, France, Germany and Russia faced social movements in 1917. Only the russian one really threatened to get the country out of the war