This really cannot be emphasized too highly. D&D itself wasn’t a planned mass market triumph, nor (as you commented earlier) VTM, nor anything else. It’s possible to look back and spot reasons, but spotting the right ones in advance just doesn’t happen. I therefore try not to fret about it, and to be the kind of interested audience people with more news want to share it with. (I had good fortune with that hearing from others early in the rises of Blades in the Dark and Mörk Borg.)There's the rub. Nobody really knows what the next big thing might be.
As for what a replacement game would be called…possibly Original Dungeons & Dragons, with a very different typography for the ampersand and mechanics similar to 5.x. Possibly D&D, like KFC and DSW.
The suggestion of CoC is interesting. Play up the Dark Ages and other historical settings with more overt fantastic elements. But actually existing Chaosium is utterly incapable of the kind of work that would take. They’d have to partner with, or sell themselves to, someone who can get more work to market.






