I think eventually the supply will exceed the demand, and everyone will be able to walk out of a store with a desired console just like that. Like it always happens.
But I do believe this gen will be a bit longer tho, we're already at 4K meaning there's no need for a mid-gen refresh models, while the base ones will be able to last very very long because I honestly don't see 8K becoming a mainstream thing anytime soon.
Realistically, the only reason I can thing of that would create a need for PS6/XS2 in 5 or so years is when the devs either fully saturate the CPUs and they won't be able to push anything any more forward, or the GPUs will lack RT capabilities to also increase the games visual fidelity.