It was actually 2022, the year when steam deck released. The proton compatibility shot through the roof. Linux now supports a far wider array of software than MacOS, even.
It'll probably be 2025, when adoption hits 5% a few months before Windows 10 support ends. The 5% will make people take Linux more seriously when looking for alternatives to Windows 10, which will increase adoption even more, which will cause hardware and software providers to offer better Linux support, which will just cause the whole thing to snowball.
The "year of the Linux desktop" was ages ago when Intel started developing drivers upstream in Linux, Mesa, and Xorg. This lead do AMD and others doing the same. None of the current developments, including Steam Deck, would have happened without that.
I'll happily eat my words if I'm wrong. If Linux reaches 5% market share for desktop use in the next year I will print this message out on paper and eat it.