They could grant access to their back catalog for something like $10/mo, and roll out segments of the back catalog over time to promote it.
Then use nostalgia-based franchise reboots and new IP (lol, but occasionally something like Splatoon catches on) to push new console sales and then slowly phase-out back-catalog support from older consoles.
You could time the phase-out with a holiday season 2 years into a new console (aligns with discounts and once initial new console buzz wears out).
Seems like a much more predictable revenue stream than hinging on the success of a new console.
You could also create leaderboards and niche competitions for the hardcore audience (Super Mario Maker has a sizable hardcore following).