PS5 could be fully compatible with PS4 and PS4 Pro plus have a greater integration of VR (no second box) and be sold at a premium price at first. It will take nothing from PS4 sales for those with 1080p tv's who aren't interested in VR until its software base has expanded of native PS5 titles. Likely based on Ryzen CPU architecture or better.
Xbox One X has failed to take off significantly and I feel a launch is most likely autumn 2019 or 2020 because Sony aren't under as much pressure. I think there is more pressure due to Switch which has shown the hybrid console format is very popular with a huge number of people.
If they do something like a combined Nintendo Switch competitor that also doubles as the VR visor for PS5 they make launch both at the same time so 2020 seems more likely.
I forsee the standard PS4 becoming just a budget console in some markets especially South America etc but in more major markets like Europe, Japan and US the pro model could be entry level. Otherwise the line up will get confusing if there is ps4, ps4 pro, ps5 and a Switch competitor (PS4P or whatever it will be called).
Resting on your laurels is never a good thing and that's when the market can be taken away from you. Switch has become a significant competitor in a relatively short amount of time. I just don't see the problem with ps4 because if its x86 based all your existing software is likely compatible anyway its not comparable to the situation where the ps2 had to feature the ps1 chipset or early ps3's had ps2 chipsets which added to manufacturing costs. They can pretty much offer ps4 compatibility without cost. Maybe its sufficiently powerful that it could even emulate the ps3 at full speed although I doubt that would happen as Sony would prefer you to buy new games rather than play your old ps3 games in addition to your existing library of ps4 games.
