Earliest fall 2018
Latest fall 2020
It sure looks like PS plans on 6 year cycles with 3 year mid gen upgrades, but Scorpio will most definitely affect this timeline. The sales of Scorpio will determine the outcome.
Sales that surpass Pro and make PS4 weak in the knees could mean a late 2018 PS5.
Sales that only compare to Pro, even slightly more, will most likely mean late 2019 PS5.
Sales that can't even compete with Pro could mean a late 2020 PS5.
A $399 PS5 late 2018 would not be a good situation. However, a $499 PS5 late 2018 wouldn't be near as bad since it would be out of some gamers financial reach, forcing them to wait to get the new console or upgrading to a Pro for the time being.
As long as BC and FC is kept, then PS can justify it because they can fall back on Pro since it will be affordable and won't be as drastic as a drop to PS4.
I would have to assume PS would rather get a full 3 years out of Pro and launch PS5 late 2019, but would also be willing to wait an extra year and reap/milk the PS4/Pro rewards just a little longer before PS5 in late 2020.
