What I'd really do, is if it really is holding them back, why not just make the game HDD ONLY? Then the people who bought the core system will have to buy the HDD just to play the game.
I agree, that would alleviate a lot of their problems, but do you think it would cut in to sales of the game too much?
I think HDD only games is where we're going to be in the future, simply because games are becoming so demanding. If everything was on a disk (whether it's Blu-Ray, HD DVD, etc...) you will still have painful load times, and I hate waiting for load times.