[offtopic]
You mean that the President goes mad and starts calling America "Britannia" and somehow the UK stops being "Britannia"? Or that the world gets reset from somewhere within the American War of Independence to cause the British Empire to somehow lose Britain but still hold onto all of the Northern and Southern American continents?
i was more thinking, the us becomes a dictatorship, crumbles to the ground, and Britain conquers it and becomes brittania, and with the huge in pour of US military technology, the events of code geass occur, but starting now, instead of when they were supposed to.