One major thing that would need to change before anything went digital only would be isps being greedy as hell and having data caps I'm not sure how common it is elsewhere but in canada most isps have these and downloading 15+gb games frequently simply isn't feasible for many people with these caps. The plan I have is pretty much the middle of the road one from rogers and allows for 60gb a month which I almost hit each month from regular internet use add in downloads and the games would cost me 2.50 per gb just to download up to a 50 dollar max. Even the best plan from rogers is only 250gb I believe which is still not very much if you're having to download it anytime you buy a large game.
Not to mention that speeds would need to increase to fibreop quality across the board and up here fibreop is still only available in a few of the largest cities for the Maritimes and as far as I'm aware not at all in other parts of canada downloading large games can take an entire day even on some of the highspeed services like when companies like rogers throttle p2p services and inadvertently throttle other things (they did it to wow connections for a while) slowing it down even more. Basically I don't believe average internet quality or speed is good enough for this to work out yet.