Sadly people can't do much with an OS that doesn't run the applications they want. Until that becomes a reality no one is paying for Linux.
There's already tons of power software for Linux (e.g. Blender) but it's not always easy to use.
I don't see why the App Store model wouldn't work on Linux too.
That would be strange firing up Word from Steam though.
Companies seem completely dependent on the Word/Outlook ecosystem. I hope this will change in the future, and not just for some other US tech oligopoly.
Sure, there are professions where that is not true (adobe, xcode, etc.), but I think most people on this forum could switch to linux without problems.