Extending the map after the game comes out. Is it still possible? 🤔

So I'm sure we've all seen images Of the map by now.

My question then would be, how would this follow through with what was said about the map expanding since it's now an island again? how would they do this if this is still the case? do you even think that they will extend the map after the release for online or single player? which ways would they extend the map?