I agree with everything here. I want to add that in addition to all the other barriers to entry you listed that a very robust support and repair infrastructure

I agree with everything here. I want to add that in addition to all the other barriers to entry you listed that a very robust support and repair infrastructure needs to be in place. These planes need careful care and feeding. Also want to add that Embraer is another .5 in your list, Brazilian plane maker that actually makes quite a few fairly large planes. https://en.m.wikipedia.org/wiki/Embraer https://en.m.wikipedia.org/wiki/Embraer