Well to be honest, I think that the colonies mainly consisted of people that wanted to escape from Europe for numerous reasons. They were to an extent self-governing, but they paid taxes to the british in return for military support etc.... The French however, were always used to having a powerful figure ruling them, but became Irate with their kind and in the end had him executed. They were unable to govern themselves properly and that's why Napoleon took over and in the end crowned himself emperor. Are we self governing? depending where you live, but here in the UK, the state has such a massive role in everyone's lives (public transport, health, around 42% of all services), that we are not self-governing people.
I say that the U.S would have still gone into the war, because if Hitler would have counquered all of Europe within Time he would have been an enormous threat.
Hitler realy screwed it up. Basically, if he hadn't been incredibly anti-semetic, he would have had more of a chance to create an atomic bomb (many of the major physicits were jews). Also, Hitler wanted to control the war personally, instead of letting his generals develop their own tactics. At the same time, he made the same great mistake as Napoleon by invading Russia.