I don’t really see “new countries” being a thing in that way ever again. The USA was new because a “new” piece of land was literally found (well obviously it was already found by other people but you get what I mean).

There is no new land to find today. You can’t just set off and create a new country - all of the land is already taken. You’ll need to work within the confines of the current countries and try your best to improve them gradually.

At least, any other approach would probably be very bloody…