I would agree that the big three didn't think they could make it work, be that for technical reasons, money reasons, limited market reasons, etc. the end result is the same.
Where I would disagree is that Boom can make it work. The amount of specialized knowledge you need in design and analysis as well as test and manufacturing facilities makes it near impossible for an outsider get in the game. Which is why there aren't any in the commercial jet engine space. GE, PW, RR and I guess Safran is pretty much it. You can't just decide you are going to do the R&D yourself and pop out a new engine in 5 years.
Where I would disagree is that Boom can make it work. The amount of specialized knowledge you need in design and analysis as well as test and manufacturing facilities makes it near impossible for an outsider get in the game. Which is why there aren't any in the commercial jet engine space. GE, PW, RR and I guess Safran is pretty much it. You can't just decide you are going to do the R&D yourself and pop out a new engine in 5 years.