With the tech (especially the SSD) inside PS5 it will be easy for Sony to do what you are describing. Instead of releasing a PS5 Pro in 3 years, they should simply wait another 2 years and then release the PS6 - which will run every PS5 game at 4K, 60FPS, with better textures and maybe with full ray tracing support - and every PS6 game will have lower resolution, framerates, textures and maybe half the ray tracing support on PS5.
Think PS4 and PS4 Pro, though with the PS6 being a much bigger leap.
I can't see how PS5 could possibly hold back a hypothetical PS6 in 2025. The limitting factor this generation - when talking about game design - was the extremely slow HDD. That won't be a problem from PS5 to PS6.







