So yesterday, I actually used the 5e DMG for the first time.
No, not to run 5e D&D. I used it for my DCC game. It was only a very short use, making reference to a couple of random tables, but it will no doubt be the first of many applications in that campaign and others.
So this was worth noting, I think, because it makes a point as to how WoTC should conduct itself from here on in.
I think, if they really want to do well within the RPG market, then part of the trick will be to keep making products that will work in this same way: books that have material that can be used even by people who will not be playing 5e. The worst thing they can do is a bunch of 5e-specific "splatbooks" full of rules and powers and other stuff that would only be applicable to people actually playing 5e, and even then only to that subset that are constantly obsessed with getting new mechanical stuff.
The best thing they can do is adventures, settings, world-books, campaign sets, and material that supplements not the side of powering-up player characters but of giving the GM resources. And present that material in such a way that is of course directly useful to the 5e DM, but also easily usable by people playing other games. Like, oh say, Pathfinder. Or DCC, or old-school editions, or GURPS Fantasy for that matter.
Make books everyone is going to want to cannibalize for their fantasy games regardless of what system they're using.
Currently Smoking: Brigham Anniversary Pipe + Image Latakia