You can see an interesting preview of the 5th Edition DMG here. Of particular interest to me, apparently the DMG will include details on firearms and alien technology! That’ll make it a lot easier to get a 5E post-apoc or science-fantasy game off the ground.
Looking at the Table of Contents (downloadable at the bottom of linked page), it seems like the new DMG will be quite a useful tool for tweaking and customizing your campaign, not just a list of magic items. I’m really looking forward to the release of the DMG in December.