Well how much on foot combat would be watered down? Think of any movie of this genre, they don't break out submachine guns and bazookas and have shootouts all the time, just a couple of gunfughts to escape from, etc. Much of the time is spent developing story, 'making deals', running around town, etc. Theres never as much shooting as would appear...
This game should rock, I really enjoyed teh first one, the driving physics are excellent. I didn't play the second (consoles suck). Glad this will be on PC.