If new third-party games come out that won't play on the PS4, then yes.

If the "next gen" Scorpio only plays current gen games, then no.

if Scorpio is considered next gen by MS, they will be woefully underpowered when Sony arrives, which will be holiday 2019 at earliest

By the time the Scorpio releases: probably 70m PS4 and 30-35m Xbox One's.

Why would anyone choose to ignore the 70m or so install base of the PS4?

There wont be next gen games from 3rd party that skip the PS4.

I think at this point generations no longer exist in way that all current gaming hardware can be connected so consistently, everything is just all over the place that they can no longer be structured in that fashion.

PS5 in late 2018 is a possibility, but it all depends on how the market reacts to Scorpio. If Scorpio can outsell Pro as well as make PS4 sweat a bit, then PS will want to push PS5 out asap. If Scorpio only slightly outsells Pro or fails to match its sales, then PS will most likely hold off PS5 until late 2019, maybe even later. Why bring out PS5 any sooner than you have to?

The PS4 is on its way to beat the Wii. Why would sony stop?

At least they dont give up on Their buyers After 4 years