this was done as a background for one of the GURPS infinte worlds powers, the Centrum
according to that game, William of the white ship doesnt drown and comes to the throne, and eventually uniting england and france into union...this eventually becomes a world spanning power, hundreds of years ahead in tech and such due to not having the medieval age last long (its never explained)
then in 1906 i think, a groupd of dissidents detonate a nuke in london, decapitating the ruling house and causing a massive global succession war which leads to both nuclear and biological attacks all over, killing off billions and leaving the rest to become nutated cannibals..
except for Terra Australis (otl australia) where a military/corporate cabal known as the Centrum take over the world (usually by wiping most of it out) turn it into a tecnocratic socialist meritocracy and then beging invading other alternate earths for their resources, and by enforcing their own principles, such as meritocracy, elimaintion of capitaslism and the universal launguage of english...
so thats one way the world could go....