The problem is that, what airlines want, and what regulators want, is now too expensive to independently develop and start a new competitor for, even if you are

The problem is that, what airlines want, and what regulators want, is now too expensive to independently develop and start a new competitor for, even if you are well resourced like China, Japan or Russia (which all have attempted and failed to break into international aviation sales). A new aircraft development is a $15B+ R&D investment, for the price and fuel efficiency and safety required. McDonnell-Douglass and more recently Bombardier messed up their bets and it cost them their independent existence.