FWIW e.g PS6, I do think that's a 2028 system. Especially if the PS5 Pro is delayed to early 2025, I doubt SIE would want that to only have a "focused" shelf life of only 2 years before a PS6 comes out and displaces it as the premier system.
However, anyone saying PS5 will outsell PS4 in the same 7-year span is being EXTREMELY optimistic. GTA6 might not end up being the phenomenon GTA5 was...and if it's not then what? What would SIE have left to push further console sales? Especially if they stick with the cadence of bringing all their games to PC (likely more Day 1 i.e LEGO Horizon, and shorter windows for tentpole titles too).
Although, at least it seems like SIE are doing other things with the console that could stimulate sales over time. They're testing a 4-part installment payment program in Brazil that should be deployed in other markets over time. If they refine it the right way (I've gone in about this type of idea in the past), it might incentivize more console buyers ad let them have more flexibility with the games they buy. Getting more features on PS5 (and console-side for PSVR2, PS Portal etc.) to better match what other ecosystems like Steam are providing, would also help in the long run.