I think it's better to say that most people that want one, have one. Platstation just isn't as dominant and popular in Japan as it used to be.
Playstation 2 sold over 23 million units
Playstation 3 sold 10.5 million units
The potential is there but Japan has transformed into Nintendoland throughout the years, nothing to do about it really.
Japan became a handheld and mobile land, and home consoles are becoming more and more a niche product for societal reasons. It's deeper than Nintendo VS Sony, it's the type of gaming changing. Mobile became bigger than console gaming IIRC, and the Switch might also hit a ceiling after a while.