But there are ways to link yourself to a brand without BEING that brand. An ad campaign during the rollout that included language like "from the designers that brought you Dungeons & Dragons 3.5Ed" would have generated a significant halo effect. That, coupled with a (comparatively) blank slate of expectations and mechanics that didn't have to shoehorn legacy concepts would have given it a significant leg up on games not launched by WotC.
4e was a perfectly fine game. But, without the D&D name, it would be faring about as well as any other game without the D&D name. So, if by "going strong" you mean "going strong compared to FATE or Savage Worlds," then yes it'd be going strong. If you mean, "selling as well as it did as 4e," then I am skeptical. This has nothing to do with the game design, and all about marketing.