I feel like we almost played out this scenario with Paizo/Pathfinder and that if this were to happen as you say, someone like Kobold Press or ENworld Publishing would see a big spike in interest for their products. At some point if the D&D trademarks don’t see actual use in products, the value of those trademarks would start to decline. It’s like putting the Beholder in a vault and no one can have a Beholder anymore in a game. Instead we have an “Eye of Terror” that does roughly the same thing (I think this is MCDM’s version of it), and eventually it becomes the norm for people.