Considering what KDE has achieved with Plasma 5, I am really happy. I use Plasma 5 on all my machines that are capable enough to handle it. Gnome 3, consequently, has never found a place. On old machines, I use Xfce only. Xfce is, in no way, for the masses. Plasma 5 could easily be the Desktop Environment that everyone loves, if they continue to improve.
I have helped people migrate from Windows to Plasma 5. They loved it. However, getting\installing software and general system management is still not straightforward enough. We also need system management tools that are solid. No terminal gymnastics at all for the common user on distros targeted at the masses.
Flatpak is all cool, but we need core user-space applications to be standardized. LibreOffice, for example, needs to become the industry standard office-suite. How can we achieve that? People I know just do not want to move away from MS Office. Even government agencies invest heavily in MS Office. This might just be the most important impediment.
I think, the Linux ecosystem shows us what a real "free market" looks like. Lots of small players and no monopoly. People love choices and they have. You want a minimal Window Manager, you got many to choose from. You want a full-blown Desktop Environment, you are spoilt for choice. Not a bad thing in an ideal world, but...