You’d be surprised at how long development cycles are for hardware. PS5 development would have started shortly after the PS4 shipped. You’ll see similar for other hardware. In all likelihood PS6 development has been going on for about two years.

For components like CPUs and GPUs, or popular consumer electronics like phones, multiple generations of hardware will be under development simultaneously in order to permit desired release cadences.

They start planning our the next console years in advance. It’s not coming till 2027 at the earliest