No one was laughing at the idea of self landing rockets, because the DC-X did it 1993, and even by then it was known that it was probably feasible within Earth's atmosphere. The issue was always around the economic feasibility of it, since you have to carry the propellant needed to bring the vehicle back, and whether or not a silicon valley billionaire with no aerospace experience could break through into the industry. I think at this point, history is on Musk's side, but I also think there were valid reasons to be skeptical.
And I'm skeptical that these guys are going to be able to type certify a new engine in the timeframe they've given. Jet engines are harder than rocket motors in some ways. Certainly the way in which they're used imposes stricter reliability requirements. They run constantly, and can take weeks to spool down, for example, when a rocket might only fire a few short burns on a mission. Realistically, I think they would need similar government support as SpaceX received to bring this kind of product to market, but that's just my opinion. It's good that they're trying, and I hope I'm wrong, but this stuff is hard and expensive.
And I'm skeptical that these guys are going to be able to type certify a new engine in the timeframe they've given. Jet engines are harder than rocket motors in some ways. Certainly the way in which they're used imposes stricter reliability requirements. They run constantly, and can take weeks to spool down, for example, when a rocket might only fire a few short burns on a mission. Realistically, I think they would need similar government support as SpaceX received to bring this kind of product to market, but that's just my opinion. It's good that they're trying, and I hope I'm wrong, but this stuff is hard and expensive.