See, thats what I was thinking, that once the new full release drops, I can just update my game/save, go on some journey and generate new terrain to find the new stuff. I don't mind traveling, but I do mind sinking my time to essentially give up and start again, because the new structures will never generate. However @ifoz made me believe thats not the case and those new structures won't show up or rather the chances are low.
I don't know how the generation works, hence me asking the questions. For all I know those new structures could be a separate generation setting that won't be active on old saves... However from player's point of view that would be a really bad move, so logically one would think devs would do anything to make it work on old saves to benefit players and protect old saves.