Currently Online 
PS5 player here who got one nearly two years after launch in 2022.
November 2028 is the absolute earliest Sony should launch PS6. And I'm more inclined to think March 2029-November 2030 is a better range. Tech prices are cooked for the foreseeable future, and a lot of pricing is as well, and big video game spending doesn't have a guarantee as recession-proof.
Gaming graphics have reached a relative plateau in resolution and polygons. 5K and up is pretty niche on Gaming PCs, and PS5 Pro only has a small amount of 8K titles itself.
4K60FPS will be more common for PS6 than PS5 Pro, and there will probably be more 120FPS support for 4K games and games between 1080p and 4K.
A lot of games take so long to make that even though I expect a cross-gen period anyway, the 7-year cycle is dead for now. Switch 2 probably won't even need to be replaced in 2032 relative to benefits of a new system and costs.
It would be wonderful for PS5 and Xbox Series X/S to last long enough to where their prices go down to at least their launch prices, if not below.
Lifetime Sales Predictions
Switch: 159 million (was 73 million, then 96 million, then 113 million, then 125 million, then 144 million, then 151 million, then 156 million, then 161 million)
PS5: 116 million (was 105 million, then 115 million, then 122 million)
Xbox Series X/S: 38 million (was 60 million, then 67 million, then 57 million. then 48 million. then 40 million)
Switch 2: 120 million (was 116 million)
PS4: 120 mil (was 100 then 130 million, then 122 million) Xbox One: 51 mil (was 50 then 55 mil)
3DS: 75.5 mil (was 73, then 77 million)
"Let go your earthly tether, enter the void, empty and become wind." - Guru Laghima
