Speaking as a non-native English speaker, I'm not sure how I feel about American imperialism replacing British imperialism in general, but as far as English spelling and phonology goes, umm… God save the king? Oh dear no… What am I saying!?
Will it? Even when told to specifically use correct British English, LLMs make occasional mistakes and also get too eager and use it in code like CSS. With careful prompting, you can probably get pretty decent results with Claude or ChatGPT but it isn't perfect yet. I'm afraid that America has won another battle in this war.