And there is no legal threat to 95% of homebrew, never will be. Why? Because I just do what I want with their IP (Wotc) and it never reaches further than my players. Most people do not publish to the world, they present to their players. Very few folks make an official doc, get it printed, add their own mechanics, build a world atlas etc.
It will stop things like the "wheel of time" (books not tv) adaption, the reasonably widely available dark sun fan made version, "one night strahd" etc.
Now that is a shame. But. 50% + of it was drek. And half of what was good rode rough-shod over other folks ideas, vision and IP and made money for the writers for it. If you are re-doing elric's world in 5th ed, you owe a bit to Michael Moorcock (which is ironic as he dis-owns it as pulp and beneath him), and owe a bit to wizards-o-t-c because you are probably re-skinning their hard work.
What is more disappointing is that Wotc is actively trying to model their monetization of DnD in the future on mobile gaming and free-to-play computer games.. I kid you not. Luckily there are basic, adnd 1st ed, 2nd, 3rd, 3.5 and 5th ed to choose form for cool playable systems, and that's if you want to stick to "original" dnd. So 6th ed, with whatever horrible monetization they formulate may well just rot in it's own lonely purgatory with it's older brother 4th edition. (which, to be fair has a couple of cool things but overall was a failure, IMO)
*edited, spelling