Don't get me wrong, my first PC ~30 years ago was TRS-80, then Apple-II, then PC, then Unix.
Unix boxes was phased out in my company because of 10X computation speed from linux box and 1/10 cost of Solaris.
I think Linux can't be main-stream, because the main-stream users are almost laymen on computers. Windows or Apple will fits them well. Linux/Unix is for professionals.
The major disadvantage (or one ) of Windows/Apple is the lacking of script support. Perl or Shell. Try pattern search in Windows? IMPOSSIBLE. Oh, don't tell me to use DOS emulator with Perl on PC, etc. That doesn't work and feel as on a Linux/Unix.
Why Linux is better now? Because they have better command set now. Try "grep -A 2 CAP *.dat | cut -d"=" -f2 | min_max" on an Unix?