The question arose from 929 thread on what COMAC should be building. I think to start off, we have to think about demand from the Chinese carriers. The big 3 are CA, MU and CZ, with their primary hubs at PEK, PVG and CAN for international flights. MU also has secondary hubs at PKX and SHA. CZ has its second largest hub at PKX (or should be there at least). If you've ever taken flight from North America to Asia, you'd see that CA/MU/CZ are often some of the cheapest/most convenient connection options.
So first, I took a look at what a real world 5000 km range from PEK would be able to access (keep in mind that real world range can be a lot less than manufacturer advertised range, Westbound range is normally several hundred miles shorter than eastbound range due to wind from earth rotation)
You will see that it covers all of India, almost all of ASEAN countries, but would struggle to reach Bali or Karachi or Iran or Moscow.
if we increase that to 6000 km
Now, you cover all of ASEAN, probably all of Pakistan and some of Iran. It would probably struggle to reach Moscow or St Petersburgh. But as a whole, this is probably sufficient range for Air China to run a robust connection operation.
for XLR range at 7000 km
Now, we are getting somewhere. Large portions of Middle East, all of ASEAN and all of Russia.
If we look at it from CAN,
This is fascinating. CAN is actually better located to take advantage of China's increased trading with ASEAN countries and India/Pakistan. It would comfortably cover tourist hotspots of Maldives and Bali.
If we look at a shorter range version.
It would still cover a majority of places that Chinese people would probably want to fly to.
XLR one at 7000 km range
This would cover pretty much everywhere you can stomach going to on a single aisle aircraft from southern China. You will be able to fly to a good chunk of Middle East, all of Iran, India, ASEAN countries and large portions of Australia.
So if we think about things from the POV of a large Chinese carriers. They have a situation where the domestic airspace is very congested, so flights are often not on time. As such, they have lost a lot of pax to high speed train. As such, sub 2 hours flights generally are not very competitive in the domestic market. For the 2 to 5 hour flight market, they need something that has very low cost since they need to compete with the more comfortable experience of taking the train. As a point of reference, PEK to SHA is scheduled in as a 2h15m flight. PEK to CAN is scheduled in as a 3h30m flight. The former would not be very competitive with trains unless you live close to the airport. The latter is still more competitive than trains (takes at least 8 hours), but would need to be competitively priced. As such, a domestic Chinese carrier would want an aircraft with the lowest CASK.
If you are operating mostly out of CAN, then you want an aircraft that has very low cost in the 2 to 5 hour range at very high density. So this of a single class configuration of around 250 passengers at 28 to 30 inch pitch. This type of aircraft would allow any domestic Chinese carrier to cover all of China, Korea, Japan, Vietnam and Thailand. Now if this carrier also wants to use same fleet type for longer flights (5 to 8 hour range), you need to have a lower density aircraft with longer range.
so, I would propose the following. Base model
single class configuration with 200 passengers, 4 flight attendants at 29 inch pitch, 2 class could be 16 FC + 150 Y. Doesn't need a whole lot of range, 5000 km is fine. This would be comparable to MAX8 -> 200, maybe 1 row longer
First stretch model
single class configuration with 230 passengers, 5 flight attendants at 29 inch pitch. This would be basically A321NEO. Again, for high density variants, 5000 km range is fine.
Low density, low range model based on first stretched model
2 class with 16 J (lie flat), 160 Y 31 inch pitch + 7000 km range.
Second stretch model
This would be really pushing things for a single aisle aircraft
single class configuration with 270 passenger, 6 flight attendants at 29 inch pitch. Can also add in a 2 class configuration at 24 FC + 200 Y. I think for this, even 4500 km real world range is fine. this would be similar to the proposed A322NEO layout.
Keep in mind that most airports have what we call Group 3 sized gates. Which limits the wingspan to 118 ft. So this aircraft would have to fit this criteria. They probably want to have winglets on them to have better fuel economy. It's very important to have the most optimal wing designed for this segment.