Unbelievable that Hasbro is doing this again after how badly screwing over third parties went the last time. D&D 4th Edition had much more restrictive terms than 3.5e; one of the big selling points of 5e was the return to the OGL. I guess they're confident that they don't need third-party content or the goodwill of the broader tabletop community anymore. But if recent efforts like the Spelljammer book are any indication, they're dead wrong about that.