1. Remove it from schools so kids don't grow up used to it
2. Stop it being bundled with new PCs
3. Get companies to stop using Excel
4. Convince gaming companies to stop making first class support for games for Windows
5. Make all existing important software and games work just as well on Linux
6. Get NVIDIA to make Linux a first-class citizen
In fact, it may not be an exaggeration to say: the only plausible explanation why Linux isn’t dominant is corruption.
Libre Office is just... not there. Something is seriously wrong with it.
Anyway, Linux Desktop is ready for the mainstream. I can typically get away with Google's suite for Office. All of my workflows work fine with Linux, and I have hobbies from 3D printing to electronics to writing to creative work.