Honestly, I hope that doesn't happen. I think if everyone started using Linux it would end up being diluted with commercial entities. You'd have Linux companies like Canonical scooping up more and more market share until they are essentially just the Linux Microsoft corporation. At that point, any decision they make becomes the defacto law of the land despite smaller independent distros/groups trying to do things differently. Other choices would exist, but basically it would be like how most linux users have to live with systemd changes because it's a nightmare to replace that without distro hopping.

You'd still see off-shoots for the desktop space, but if you want to use <INSERT_X> then you have go through this company.