Consoles are getting to a point now where they're not even trying to hide the fact that they're just glorified PCs anymore.
Not glorified, but dumbed down PCs. 'Glorified' is a term you use for something superior, i.e. the PS5 launch title Spider-Man: Miles Morales is glorified DLC because it goes beyond typical DLC. The PS5 and XSX, however, are much more limited than PCs.
As for your prediction, I don't see it. The various console markets of the world have their own dynamics, so if we go over them briefly, we get this:
1. Japan will see continued decline for PS+Xbox consoles, because there's no population growth and the demographics are getting older while the game industry does not want to adapt to this changing market.
2. North America, the western half of Europe and Australia will remain about flat because the populations continue to grow due to immigration. There will still be plenty of kids, so older gamers switching to the PC because of increased options will be offset by the next wave of kids getting a PS or Xbox.
3. The eastern half of Europe and the rest of the world continue to present growth opportunities due to raising wealth of the common person.
Beyond that, the game industry will continue to want PS and Xbox to succeed because the closed ecosystems of consoles put gamers in a virtual no-choice situation, unlike the PC. If it's necessary to give the PC the short end of the stick, then that's what the game industry will do to accomplish their goals. Therefore potentially high launch prices of new consoles will merely be an obstacle in the short term, because eventually lower hardware prices and continued preferential treatment for PS and Xbox consoles by major third party publishers will steer the market towards the direction that it is supposed to go in.
Lastly, the casual appeal of PS and Xbox consoles is that they aren't as complicated as PCs, so that is covered.
In the sum you are best off to expect continued stagnation of the global market size of PS+Xbox combined, because the declines in some parts of the world are going to be offset by increases in other parts of the world.