Without the success of the American Revolution as an example, the colonies in Latin America might not have had their own independance movements. Spain and Portugal might still be colonial powers. Alternately, when these two powers grew weaker, and with no Monroe doctrine, other European powers (or maybe Japan) might have tried to take over in central and South America.
There probably would not be a centralized American or Canadian government. London understood it was in its best interest to keep the colonies divided into seperate governments.