Well PS3 didn't destroy Xbox 360, but it actually caught up in 2013, after years of efforts and great games...
That's despite launching full year later, and even longer in Europe (March 2007) and having awful price...
And he's right, Xbox Scarlet will have even worse sales compared to PS5, I'm betting on 75% to 25% between Sony & Microsoft next gen.
At this very moment with these August 17th 2019 sales it's actually 69% PS4, 31% Xbox One, that's really awful after massive success that Xbox 360 was last gen.
But what do your predicted % with Nintendo thrown into there? And yes, I know many buy Nintendo devices in addition to PS or XB, but there still are those who exclusively buy them rather than the other two (like me). You think Switch/Switch 2.0 will hold it's own?