OP definitely has a certain kind of perspective. I think it would be more accurate though to say Japan's console market is consolidating. It is mostly consolidating into the Switch. Most Japanese gamers from Gen 8 are just buying a Switch for Gen 9.
3DS -> Switch
Vita -> Switch
Wii U -> Switch
PS4 -> PS5 and/or Switch
XB1, LOL -> Series X, LOL
In the end Generation 9 hardware in Japan will mostly be the Switch. Less hardware will be sold, because in Gen 8 some people bought both a home and handheld system while in Gen 9 they only need 1 system: the Switch.
I voted "Japan is games", but I wish there was an option for "Japan is Nintendo".