SpaceflightMemes

Your best indication would be what happened in France to the language since 1600, and what happened to French in Quebec since 1700. To Parisians, Quebec French sounds archaic and coarse, but it's developed and changed a lot, millions speak it in Quebec so it's formed it's own divergent path from a common base dialect, which apparently back then sounded a lot like a German speaking French, as modern Quebec French also does. Anyways, some sort of isolation and lack of regular exchange will have to develop to prevent both languages from continuing to match, which a space colony with a base stock from one nation and permanent residents would pretty much be, as long as they are not watching the same TV shows as on Earth