I would prefer to just keep this generation going until we have lots of games that are hitting the ceiling of what's possible. Every generation, there are fewer and fewer studios that can afford to truly max-out the technical capabilities of the new consoles, and I'm not sure we've even really seen ONE game yet that I would describe that way.
Most of Sony's games have dual-launched on PS4/PS5, and usually their first party teams are the ones pushing the envelope the most. Spider-Man 2 looks good but I refuse to believe that it's the height of what the console is capable of...I want to wait and see what Rockstar/Naughty Dog can really do with this thing, when it's not held back by a cross-gun release.
Developer demand should dictate launch timing for new consoles...not the imaginary need for an 8 year cycle.