As great an idea as this is, I don't think I want it.
IV is inconsistent enough with only 16. The game has changed -- not so much the console. I would prefer flawless 16 or maybe 20 over clunky 32. If they could fix it so that people in the same vehicle see the same thing at all times (unless there's some serious lag), that'd be more than enough for me.
GTA IV freeroam is the best thing evar, but it still could use some polish. Seeing yourself shoot someone with a sniper rifle or mow them down with a vehicle only for them to get up and rocket you sorta sucks.