If an OS is used, then that's because people need it, not because they're fighting some imaginary fight in the jungle. It's their preferred OS. If the number of people using computers shrinks, because non-pro users move to mobiles, while the fraction of pros using Linux increases to 95%, or even 50%, I think that's a very clear win for Linux.
The reason why MacOS grew in popularity is because it started to be used by pros, myself included, i.e., I've switched from Linux to MacOS seeing many top computer scientists using MacOS. However, after over 10 years of using MacOS, I'm actually still not sure whether it was worth it, and I'm considering to go back to Linux since a few years. The main reasons stopping me from switching is a reliable Calendar app and concerns about battery life.