I think most important is that C919 may have a greater effect on competition with Airbus and Boeing than Bombardier and Embraer simply due to the size of commercial jet market in China.
The effect could be price cuts/ greater incentives from Boeing and Airbus to airliners which is good for us the air travellers.
Now that's what I'd call a well thought out post.
Indeed, China's size alone ensures COMAC will be a much greater threat than Embraer and Bombardier, which btw is going bankrupt, both of which Boeing and Airbus never really cared about.
Speaking of choices for travelers and airlines, A320 and B737 were the cash cows of which they were happy to keep milking well into 2020s while struggling with A380 & 787.
C919 was the first to announce a date pre-2020. A strategically smart move going after the jugular in this segment forcing the other 2 to respond at a time when they much preferred to focus on other segments.
Airbus seems to have responded well with Neo. MAX is looking less comfortable.