I am going to use Germany as the example for this post, but I don't see why it couldn't apply to France or Britain.
Germany is a nation of over 80 million people. For all intents and purposes, they have one German carrier to choose from. Sure, Eurowings flies some routes (and I love them, being an old NFD fan), but I wonder what's to stop an upstart airline from challenging Lufthansa on scheduled international and/or overseas routes, like British Caledonian used to do with BA.
I am writing in total ignorance of EU and German regulations, and I imagine those have something to do with it. Please let me know if I'm wrong.
Personally, I'd love to see Eurowings grow into a mid-sized international carrier, offering point-to-point overseas connections to underserviced German cities. NUE-EWR, for example, or Berlin-BOS. Wishful thinking, I know, but, while I'm dreaming, maybe a Eurowings A340 flying Berlin-Tokyo? I need a beer.