We need to learn to recognize the difference between something that's never going to happen for either physical or economic/social/structural reasons, and something that is just really difficult and takes a long time.
I always think of this when I think about fusion and the irritating "fusion is 20 years away and always will be" meme. In reality fusion has been edging closer, and closer, and closer for decades. Like EUV lithography it's just incredibly hard and requires a ton of capital and time and some of the smartest people on Earth to make it a reality. The same logic applies to things like a working HIV vaccine, life extension, or human space flight and space settlement.
The reason there's never been a year of the Linux desktop on the other hand has to do with the full picture of what's required to mass market a desktop OS and support that, not just the technical problems, as well as business reasons around what Microsoft does to incentivize vendors to stay in their ecosystem. Linux desktops are just about ready today but no mainstream laptop/desktop PC vendor is going to sell them for a long laundry-list of non-technical or para-technical (legacy software base) reasons.