Everyone has their own theories for what can/will trigger the "year of the Linux desktop."
The reality now is that desktop computing in general is becoming niche. Sure, maybe pre-installs well help, but personally I don't think so. More and more regular people get their computing done on their phone, or maybe a tablet. Why? Because the majority of people aren't creating things with computers, they are just consuming.
For those that do still need "desktop" level/general purpose computing, OS doesn't matter as much as app compatibility. Steam is helping this along in regard to gaming, but what about everything else? macOS wins here over Linux, and will be more likely to pick up any stragglers.
The reality now is that desktop computing in general is becoming niche. Sure, maybe pre-installs well help, but personally I don't think so. More and more regular people get their computing done on their phone, or maybe a tablet. Why? Because the majority of people aren't creating things with computers, they are just consuming.
For those that do still need "desktop" level/general purpose computing, OS doesn't matter as much as app compatibility. Steam is helping this along in regard to gaming, but what about everything else? macOS wins here over Linux, and will be more likely to pick up any stragglers.