but his roster spot would have to be filled by someone who can score as effectively
That might be easier than you think considering Bargnani isn't some extraordinary scorer.
Finding someone who will give you 45% FG, 34% 3pt and 5 FTA per game while giving them 36 mpg, tons of touches on offense and 18+ shots per game shouldn't be hard. That is if you're looking for an SG with that kind of production. You'd never want a PF/C like that.