Maybe if certain platform holders got more creative with their offerings on their console in terms of features and software variety exclusivity to better compete with other gaming devices that aren't necessarily consoles, they'd actually be able to grow their install base.
And if all the platform holders did similar moves (or at least the two that seem more in need to do it; Nintendo seems the exception), the total addressable console market size would grow. I mean we saw that happen in the 7th gen, because all three platform holders were hungry and wanted to maximize their respective console offerings.
This gen? It's mostly been more of the same as before, complete complacency from one (Microsoft) and creeping complacency from another (Sony), when it comes to fully maximizing the offering of their consoles. It's like a restaurant chain getting lazy in their service and recipes and then complains the entire restaurant industry is in decline. No, maybe it's just your restaurant because you need to innovate with your restaurant, not think you can just put your stuff in other restaurants and suddenly reverse fortunes.
These companies have to take accountability for their own situations and stop acting like the market itself is the problem.