Of course it wouldn't stop colonialization, but it would change the future quite a lot.
- No English-speaking superpowers/English as lingua franca
- No Commonwealth
- No wide-spread anglo common law based legal systems
- Superpowers/alliances would be totally mixed up up to now.
- China could have developed totally different due to them not constantly losing against the English.
- No colonialization of the Welsh, Scots, Irish by the English
I think that should shake up the timeline quite a bit.