PC ownership is NOT a zero-sum game. You assume that lost marketshare must be replaced by something else. I'm confident this is not people replacing their PC for a Mac, this is people who stopped using a PC completely.
Microsoft, by ruining Windows, is not leaving the field open for a replacement OS; they're slowly killing the PC itself.
Mathematical: If this were the case then all competitors would have seen an increase in marketshare proportional to their existing marketshare. This isn't what happened - Mac saw 3x the increase of Linux, even though Linux has greater marketshare on the survey.
Statistical: It's often said that the PC is dead or dying, but that's a misrepresentation of the issue. 25 years ago, a new computer was dated in 3 months and obsolete in a year, so PC sales were huge. Now a days, a ten year old PC is still fine for just about everything, even including relatively high end gaming. So sales have plummeted, but ownership rates are around historic highs. [1] The main limiting factor is money. More than 96% of households earning $150k+ have a desktop/laptop, while only 56% with income less than $25,000 do. The overall average is 81%.
Pragmatic: PCs are still necessary for many types of games as well as content creation. Mobile devices and tablets (to a lesser degree) are limited by their input mechanisms to a subset of all experiences, and there's a pretty big chunk of people that utilize experiences outside that subset.
I don't worry much about that. I has been often said that PCs would be dying. Seems it was mostly marketing. It survived consoles and Xbox is probably dead. I have no illusions that Microsoft has the same mismanagement in store for Windows, it didn't have sensible patronage for years.
I don't think it's dying, what I think has been happening and will continue to happen is that unless you're an enthusiast the PC presence is gradually being shrunk and tidied away in a corner and forgotten by many. For many having a 'home PC' would be a relic, similar to how they don't have anything like a dedicated stereo system for playing audio which might have taken up a significant amount of space (possibly more than a PC) years ago.
This is definitely not the case. PC ownership is near record highs right now. I cited the stats in a peer comment. [1] The only real hurdle is perceived cost. More than 96% of households earning $150k+ have a desktop/laptop, while only 56% with income less than $25,000 do. The overall average is 81%.
Mobile, and to some degree tablets, just offer a generally poor interface for many aspects of computing from gaming to content creation, and I think that's mostly intractable.
Sure, but I guess this depends on what model you have of someone doing media consumption, are they going to fire up their PC to watch/listen to media, or their phone, or (smart) TV, or a smart speaker?
Microsoft, by ruining Windows, is not leaving the field open for a replacement OS; they're slowly killing the PC itself.