Well, if it's any indication, my sister, who is very much not a tech person, randomly asked me to help her install Linux Mint a month ago, and has been using it successfully since without needing to ask for help once (at least not from me, I suspect ChatGPT is getting a workout).

That felt like an indicator to me. I only switched to Linux a year or two ago and haven't mentioned it to her once, so she got the idea from somewhere else, and had enough impetus from whatever she disliked about Windows to actually go through with the change. If I was in marketing at Microsoft I'd be shitting myself over that, assuming Windows even still fits into their long term plans somehow. It's one thing for 100,000 techies to preach Linux across the web, but if random normies start using it without fanfare, that's real change.