VELOCITYG4,
Microsoft and Sony both hate the idea of constant hardware updates with higher specifications... first they make their money off the SOFTWARE and secondly it's a huge hassle for game developers to support multiple generations even if they are very similar.
I think we'll see an approx 2020 PS5/XB2 release for new hardware with an emphasis on 60FPS and by then the visuals on average are going to be truly incredible so there will be much less desire by EVERYBODY to buy new hardware... I mean what if a game looks almost photo-realistic and runs at 60FPS, so what you come out with a 20% graphics hardware update that would likely look almost identical anyway?
No. If see new hardware in 2020 I fully expect to see that hardware last until at least 2025 (not counting die shrinks). The PS4 PRO and XB1X thing is unlikely to be repeated since again visuals will be awesome and 60FPS should be the target... in fact, with backcompat in the x86 designs games will mostly support the PS5, PS4 Pro, PS4, XB2, XBox One/One S, and XB1X so they really don't want to add yet another console to that mix if they don't absolutely need to.