I don't remember if it was described. I suppose people don't write time travel into the future because nobody knows what's happening in the future, so it's not a place you'd go to fix anything. It'd be a cool place to go look around, but I don't have enough imagination to come up with dramatic possibilities.

If you went there just to look and saw something really horrible, though, that would be good excuse to try to change it when you got back.

If you lost your time turner in the future, there'd be no way to get back.

If you time turner yourself into the future, have you grown older, too? You might be dead! I could see Harry wanting to know what happened . . . People assume that if you go into the past, you don't get younger or disappear.