It was very plausible for the Rebels to get the Quebec province in the revolution. The US would just have to have led a successful invasion (IE, taking Quebec city [either that or Montreal. I can't remember.] and cutting off supplies from traveling along the St. Lawrence to the other Canadian cities -Toronto and Ottawa, etc.- and Canada was pretty much just those cities back then. Instead what they did was lead a three pronged attack against three cities instead of "cutting off the hydra's head" with a singularly focused attack on Quebec, which led to forces from a beaten Montreal fleeing to Quebec and therefore Americans lost there.). There were many supporters in Quebec (they managed to form two regiments to join the revolution), and many who didn't really care who was in charge who could be open to a union with the "United States" as the 14th Colony/State. Other than that, all I see the US doing is what it did in the OTL. Sparking the idea that any colonial people could rebel against its conquerors with enough resolve.
If it failed, the "founding fathers" would have been hung as traitors, and America would have been put under the British crown again. Maybe it could be granted dominion status or members in parliament (which the Americans didn't even want, btw. That whole "No taxation without representation" stuff was just a slogan. The Americans knew they would be far to outnumbered by non-colonials to do a thing), but that's it. The Sons of Liberty would likely form into sort of the colonial Vietcong if they survived, and could still exist to this day in the ALT as a "terrorist" faction fighting to get America independent in a guerrilla war.
