Since Divinity 2 will have a full 3d engine, it would be just a matter of changing the light and of course, gradual change is possible.
Rest assured, Kris: as Hand-E-Food said, portable lightsources should lighten things a bit <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />.
Don't forget that you can always adjust the game's gamma. It might look ugly but it is an option if you can't orientate in the dark.
