Anything you walk into may not change/update later. See the H&H example of tar pits only spawning in new never seen before plains, not your old hunting grounds.

however a DEV or dev rep said that you should expect to start over at game launch if not before. So some future patches may totally fail on old worlds anyway.

So, you can explore some of it, but it may not update properly later. Leave most of it be, seems like a better idea.