This isn't their first time (the ARJ21 was). Will COMAC succeed where Mitsubishi (Japan), Bombardier (Canada), Sukhoi (Russia), and Lockheed (USA) have failed? Maybe. But China's set a deadline of 2025 to have their own homegrown product in service and it's doubtful that specific goal will be met.

The western aerospace industry is hardly betting against China here. I think Airbus was expecting COMAC to be competitive by 2020. Hell, a huge part of the reason that the 737 MAX exists today is that the Boeing CEO thought China was their biggest threat.