[citation][nom]jkflipflop98[/nom]Valve could do the game justice. However, we would have to wait an additional 12 years for it to come out.[/citation]
Valve doesn't have the right attitude to make DNF. For it to be a real sequel, it has to be aggressively juvenile in tone, and Valve hasn't made anything like that as far as I know.
Croteam could probably do a decent job, possibly Rockstar, and a few other developers... but really a game like DNF would go over horribly today. The average age of gamers has gone up substantially and the people who played DN3D are nearly all in their twenties or older, so the kind of stupidly juvenile humor that characterized Duke would be pretty soundly rejected by the target market. They'd probably claim it sucked and wasn't the same, but really, that kind of thing simply doesn't appeal to anyone over about 13.