It's sheer speculation as to what might have happened after the war. The British Empire didn't wilt because it lost most of its North American colonies in 1783, and it never damaged the interests of the Crown or British prestige and power abroad not to have exclusive control over Ireland.
The results of the war benefited the Northeast and old Northwest greatly, while leaving most Southern citizens in the same economic status as serfs in Czarist Russia. In addition to the Roosevelt commission on Southern poverty (1937-38), there are two excellent studies of the impact of the war which I would like to mention. The comparison to Russian peasants comes from one of them.