A320NEO was started as a response to the C Series, which has now become quite a monster under Airbus. But keep in mind Airbus still looses money of every A220 it sell. For most airline projects, you lose money in the beginning and don't make money until you reach certain volume production. It's hard for me to know the profit levels for C919, but I assume it is going to be losing money for a few years.
As such, it was quite important for them to not wait longer and get C919 certified already. The longer you wait, the more money you spend and the more pressure there is on COMAC. As such, it is absolutely the right decision for them to use Western suppliers. the next step for C919 is not range. If I'm an airline in mainland China, I'm not too concerned about its range. It can fly any domestic sectors or to Thailand, Japan and Korea. Most of the airlines in China operate multiple short haul fleet types. It's not one of those things where they need to buy 1 fleet type for all the mission types. Once you get to a certain size, being able to operate different fleet types that are optimized for different missions is more important than having fewer fleet types.
With B737 not longer being an option for Chinese airlines, it is very important for them to operate a non-Airbus fleet type in order to obtain large discounts when place A320NEO orders. And that's not even factoring in all the geopolitical issues associated with Western aircraft. So, not that I covered this, it should be obvious to everyone why Chinese airlines must operate C919 as a subfleet.
The most important part for COMAC is to work with the airlines to establish after service support and developing maintenance centers. Whenever an airline adds a new fleet type, it's a big investment. It needs to establish a new pilot rating, have separate list of pilots just to operate that fleet type. You also need mechanics and support staff to maintain that new aircraft types. You need to buy flight training simulators for that type. Your pilots need to go through training on that type to "stay current". You need to be able to have relationship with the supply chain so that you can get spares and work out regular maintenance schedules. You have to think very hard about where you can operate that aircraft since there aren't as many mechanics for that new aircraft. As such, if it breaks down somewhere, you need to have mechanics there to be able to repair it. Hangar queens are a huge problem for new airline types. These are all things that take huge investment by the airlines. So the big 3 Chinese airlines are not going to stop at 5 aircraft. Don't be ridiculous. This level of fixed cost investment doesn't translate to 5 aircraft. They will order more by exercising their options or leasing one of the several hundred C919 on order with Chinese leasing firms. It's great that COMAC will be able to work with all of the big 3 airlines to get better at this after service support.
Also, keep in mind that having a large domestic market means C919 will get at least 500 orders. When you have that many aircraft in service, there will be a secondary market and plenty of spare parts. All of these reduces operating cost and risks for airlines purchasing new C919.
So don't concern yourself too much with range. Think about how quickly COMAC can get better at after service support and making airlines happy. Believe me, the big 3 Chinese airlines are not going to be enjoying flying C919 in the beginning. The first legit aircraft type by COMAC is like to have as many problem as Embraer had with E90 (might be even more).
As for indigenizing subsystems, they will obviously have to work toward that. Having a fully Western free supply chain will allow them to sell to domestic ministries, CIS countries, Iran, Venezeula, Cuba, Myanmar, North Korea and any other sanctioned countries. If C919 is successful, it will be able to sell beyond that. Don't worry too much about initial export order book. Get C919's support system worked out so that new airlines will be able to add it into their fleet more easily and then work toward fully indigenizing.
Don't worry about comparing yourself to A320NEO. Just get it to be something airlines can use.
