I think the Scorpio will make XBox peak in 2018 I also expect a lot of good games in 2018 from microsoft, the next playground game from their forza horizon studio, halo 6 should arrive, 2018 will be a very very strong year for microsoft.
I expect PS4 sales to either have peaked last year or peak this year because this year ps4 has a much stronger software lineup compared to xbox and the pro has recently been released and should get a price cut when microsoft start their Scorpio advantage
Competition is great, competition is necessary lets hope both keep doing great
Twitter @CyberMalistix