Well, it certainly won't happen for the next several years, at least. Let me put it this way: If any of the big three released a system that did not support retail software, EB and most other enthusiast outlets would outright refuse to stock the consoles, and the systems would tank since they'd be sold in far fewer places.
As for the ratio of digital sales to retail sales, I assume we're talking consoles only, as downloadable software overtook retail on PC years ago. On consoles, it depends on what you define as 'retail' and 'downloadable'. For instance, Nintendo recently announced that all of their games for Wii U will be available at retail, both on a disc and via a download code. You can buy the download code at retail, but it is still downloadable. Which category do we classify this under?
Different experiments and strategies such as these will determine the answer to the question.







