Unpopular opinion but the answer should be self-evident and has little to do with technical merit: cheap and just barely good enough beats expensive and better every time. And Linux is free as in beer. It's not unlike reports of how generous food donations to poor countries bankrupted local farmers; it's impossible for a wannabe new OS vendor to afford to pay its engineers long enough for their OS to gain traction over the incumbents, particularly when one of them is free.

The only two options I see are either one of the FAANGs spend the billions necessary on the long, hard slog to push a next generation OS until it takes off or another person of Linus Torvalds' stature pops up out of nowhere again to build an OS so amazingly good that it takes off on its own like Linux did. Both scenarios seem improbable.