·Verizon Online DSL
The delivery cost for a 4GB game (we'll assume it's small enough to fit onto a single DVD) is maybe 40 cents over a nice, expensive CDN these days. Double that if someone loses the game and has to reinstall. That amount won't even pay for the disc and jewel case for a boxed version of the game, let alone transportation etc. of the good.
If licensing for digital content starts to make sense, and pricing of said content becomes more in line with the cost to provide it, then we've got a model that everyone can agree with.
Heck, I already agree with it. I would much rather download a game and play it (whether straight or by mounting a disc image via DaemonTools) than fiddle with a disc. Then again, I have a 2TB hard drive on my primary computer, which will be replaced by a computer with a 2TB HDD and a 256GB SSD tomorrow.