> will end up being the only mainstream Linux desktop because of its corporate backing
Ubuntu, Fedora, SUSE, Pop!, Deepin (and the list goes on) all have corporate backing. Steam is a well-known consumer brand though, so that might make a difference.
I don't think the usual distros care about the desktop experience as holistically as a long-term consumer company that Valve is. Otherwise one would expect Linux distros would be much better than what they were even 10 years ago.
Ubuntu, Fedora, SUSE, Pop!, Deepin (and the list goes on) all have corporate backing. Steam is a well-known consumer brand though, so that might make a difference.