so do we have enough engineers who care about maintaining useful tools that aren't handicapped or compromised to be able to support this endeavor? i think we do. there have to be many good eggs within these companies who die a little inside each time something like this goes through.
Only because those alternative mobile OSes were, frankly, crappy in comparison to iOS and Android.
I don't recall Google or Apple doing anything particularly anticompetitive to cause any of those OSes to fail to keep up in the market, aside from just plain "being the 800lb gorillas in the room". (Not saying they never do anything anticompetitive, just that those particular market failures can't be laid at their feet.)
It would be great to have some really good alternatives to the mobile duopoly. Hell, if we had more fragmentation in the market, that would even lead to more impetus for interoperability and common standards—which we desperately need more of everywhere in tech these days. But those three, in particular? They lost because they were worse at being a good mobile OS for most people.