Oh I don't doubt that at all. From what I understand, Gearbox basically finished off what 3DRealms had done and made it how they (3DR) wanted it, and then released it. They just supplied the grunt, as it were.
In their own right though, they might be able to come up with something awesome; who knows? And while I hope a lot of people/investors realise this, you've gotta admit there'll be a lot of people very wary and maybe not willing to give them a go, just being cautious.
If they manage to get another DN game out and it's actually good, then they'll blow everyone's socks off.