I think they might mean that Windows is ultimately a dead end. I agree that its far from dead, but Valve really got the ball rolling with Proton.

Now that there's a bunch of bigger influencers "trying Linux" as a daily driver and often having a good experience, coupled with Windows/Microsoft shooting themselves in the foot every other month, I think we're seeing a shift in people's perception (at least regarding what their possible options are). That said, Linux still has a ways to go until it even breaks 10% desktop share, and I don't think it will be a threat even to Apple until Linux hits 15%.