I understood it as this: David Twohy had wrote a trilogy of films, Chronicles of Riddick being the first, but since it bombed, Universal opted not to make the other two films. Looking at the scope of Chronicles, its clear they intended this trilogy to be an uber-blockbuster endeavor. I bet a Chronicles 2 will never happen as intended. If it ever did get made, it would be a lower budget affair like Pitch Black was. Good luck getting financier's to back a sequel to a film that bombed considering its production budget.