Linux already is mainstream, just look at the success that Android has had.
And there are still competing frameworks out there that are objectively better than the decided on counterparts.
ALSA replaced OSS, then OSS4 came out. The latter is more stable and can do more things than the former can do alone, such as per application volume controls, yet it's only used in the BSD sphere.
Likewise, OpenRC is a great replacement for SysVinit without changing the overall structure of the init system, unlike systemd which attempts to consolidate all of those parts into 'optional' modules that other projects are making compulsory e.g. Gnome Shell has a hard dependency on systemd as logind cannot be used alone any more, not to mention the large changes to the init design.
And there are still competing frameworks out there that are objectively better than the decided on counterparts.
ALSA replaced OSS, then OSS4 came out. The latter is more stable and can do more things than the former can do alone, such as per application volume controls, yet it's only used in the BSD sphere.
Likewise, OpenRC is a great replacement for SysVinit without changing the overall structure of the init system, unlike systemd which attempts to consolidate all of those parts into 'optional' modules that other projects are making compulsory e.g. Gnome Shell has a hard dependency on systemd as logind cannot be used alone any more, not to mention the large changes to the init design.