Then they will be the last console gen that makes this kind of money. *shrug*
For $600 hardware and $100-$200 SDD costs people can simply choose to get into gaming PCs instead, if all they have to show for it are digital libraries and paid subscriptions. There would be nothing exclusive to be gained by owning a console. It just becomes a poor man's gaming rig.
Industry people and consumers alike don't respect the fragile nature of these console ecosystems. When the core gamers decide something isn't cool anymore, and they're 'out', then things cascade down even further and more and more people leave that ecosystem. Just like how it happened with the 360 launch, and again with the PS4 launch.
Generally speaking, lots of people also don't spend 'new release' type money on digital games. Maybe once or twice a year for the big titles they want to play like Madden and CoD. But digital buries fringe and recreational spending. Gaming IPs get devalued to, "is it twenty dollars (or less) yet?" Developers do not want that. There are Indie darlings that do well and then the rest of the third parties have trouble getting discovered on Steam now, or becoming part of the cultural zeitgeist / public discourse.
How many of the "Top 20 Games of the Year" did all of you buy digitally during the previous two years hmm?