New world objects will not generate in areas that were generated pre-patch.

The only new things you might see in old areas are mobs, so long as their spawn conditions don't have dependencies to any other structure/object.

E.g You can find abominations in old areas because they can spawn anywhere that is Swamp. But you wouldn't see growths spawning in Plains without a tar pit.

Since the game first launched on Steam they have made old maps forward compatible, as in they will still load on a new patch. However the devs have been careful to avoid any assurances that this will always be the case.