The arrangement of stones at the starting point is always the same and the area surrounding it cannot be built on or terraformed by normal means. With those constraints in place I don't think it would be impossible to automate a way of placing new boss stones in a pre-existing world.

In any case, making a world now was always a risk. And if they can't automate the inclusion of new boss stones, maybe it would be possible for a player to drop them in manually with commands or mods and still have functionality.