Previous interviews I've read with Twohy have said that, without question, the new Riddick movie would be (1) cheaper than the last one and (2) rated R (which is part of why it would have to be cheaper).
Without question
The Chronicles of Riddick was one of the most ambitious sci-fi movies to come out in a while. Unfortunately, I don't think the story is nearly as interesting as the universe that it is built in. However, the ending left things wide open for many interesting new possibilities, particularly with Riddick as the leader of the Necromongers.
Part of where I think the movie turned off a lot of people was with the drastic change in the nature of the universe from
Pitch Black to
The Chronicles of Riddick. They went from a pretty straight forward technology based future into a total fantasy realm. If they had done it the other way around, I think people would have had an easier time buying it. Someone in another thread once compared it to if you made a sequel to
The Maltese Falcon which revealed that Bogart's character was the descendant of an Elf prince from Middle Earth or something.
I certainly concur with the comparisons to
Dune. I discovered a much greater appreciation & understanding of
The Chronicles of Riddick once I had watched David Lynch's
Dune.
I read with interest that Vin lobbied hard to get Judi Dench for that role and I agree with him - the mentor figure for a hero *must* be cast well! Otherwise it just doesn't work.
In some movies, that's the ONLY thing that works. (SEE Jeremy Irons in
Eragon.)