It's definitely going to hurt D&D, and I can totally see D&D getting overtaken by other RPGs. But D&D is much more than just a game; it's a brand and cultural icon on par with Star Wars. Hasbro still has the name. They can merchandise the hell out of it. The game will exist, and even if much fewer people will play it, the rich history of D&D will still be attached to it.
> Hasbro pulling an Elon is not them “learning from their mistakes”, it’s just another offense.
They think they're learning, but they're learning the wrong lesson.
What they don't seem to realise is that the editions that used the OGL, are their most successful editions. And 4e that didn't, wasn't. Ryan Dancey (one of the creators of the OGL and VP at WotC at the time) even suggested that Paizo's Pathfinder system may have contributed to the success of D&D 5, because all the players who were disappointed with 4 could keep playing a game very close to D&D, and when D&D 5 came along, many of them switched back to D&D. Without Pathfinder, they might have strayed further and not have come back. Hasbro sees Pathfinder as the enemy, but it's not. You can be big together, and the OGL did make the RPG industry much bigger than it was before. I hope Paizo's new license will do the same.