The next areas that are being made are the Ashlands and whatever the north area is called (I forget). The Ashlands are all the way at the southern part of the map, while the northern area is all the way at the north. As long as you avoid those places, they should update just fine when their updates happen.

That said, there's no guarantee. Any update at any time might require, or at least recommend, starting a fresh world. Such is the process of early access.