from the first 100, 45 were options. Each of the top 3 airlines ordered 5 firm and 15 options. At some point, those will be firmed up or they will sell the 5 top someone else, because you are not going to operate a fleet of 5 aircraft of one type. That would be a logistical problem. I'm assuming that these orders from ICBC and Sichuan are all firm, since they did not state otherwise.
Even the firm orders aren't truly firm; while they are 'orders' in a sense, the buyers apparently have the right to walk away from the contract without paying a penny in cancellation penalties. If you tried that with a more established manufacturer, they would be levying heavy fines for walking away from the contract.
This aircraft will get some good orders even if it's not up to the specs, because domestic airlines will be under pressure to at least buy small amount of it. Outside of that, all of the countries that can't buy boeing/airbus airliners that have been buying Tupolev aircraft will choose between this and MS-21. I'd think C-919 would take away a good number of that order due to political considerations and generous loans. I think COMAC is going this the right way. It's trying to establish as many partnership as possible. Although, it's hard to say how many of these partnerships will bear fruit.
Nobody buys aircraft because they are cheap. They buy the best they can get their hands on, even if it is second hand from a reputable manufacturer.
As for C-919 vs MS-21, most of major Russian airliners have already placed huge orders on MS-21. That's how it got to 200 orders. The Chinese market has potential to put in much larger orders. So, I would not use the current order total to determine future success. Give both aircraft another 3 to 4 years and oversea markets would see where they are at and decided if they are worth buying. Remember, Airbus and Boeing have already entered the picture with new engine options, so C-919/MS-21 have lost out the fuel efficiency advantage that they originally claimed. What C-919 does have is production slots and lower pricing and generous loans.
The Chinese airlines had to be heavily arm twisted to order the C-919, and they only did in small quantities. The Russian airlines did so at their own accord, and are starting to win export orders as well (50 MS-21's were sold to Crecom Burj Resources in Malaysia).
We will see, even if Ryan Air and BA never place any orders on C-919 (which is likely), it will be good for COMAC to go through this process with them to gain experience over what these airliners expect. ARJ-21 was clearly developed just for the Chinese market, but C-919 is supposedly developed for the world market, so it has much higher requirement.
Looking back now, COMAC probably made quite a few mistakes originally in its development process for ARJ-21 which is causing all of the delays now. That's nothing new for a kid in the block developing its first airliner. MRJ has the same problem.
A few mistakes? You call severe issues with certifiably that can affect safety (wing failure before ultimate load requiring redesign, flight control software that needs to be totally re-written, etc) a few minor mistakes?
The MRJ is actually doing very well in terms of development, as everything is right now set for delivery in 2014. Mitsubishi has the industrial capability and a solid history building airplanes or large sub-components of airplanes, backed up by Boeing's partnership.