The issue is that the A321XLR isn’t as capable at flying cargo as other planes. Not a problem for most leisure airlines, but it is a factor for network airlines or cargo heady markets like Latin America.
The 737-10 will have more cargo volume than the A321. Being able to fly cargo beyond passenger bags can help make flights profitable. The A321XLR is less cargo volume than widebodies or the 737-10, so airlines may choose to bulk load to allow more cargo on board. Containers add weight and reduce useable volume.
When you want to compare the 737-10 to the A321 you should define what version you are talking about. But we can start and go through the posibilities.
The 737-10 will have a MTOW of about 90 t, the OEW is not know yet, but we should look at 737-8 numbers. MTOW 82 t, OEW 45 t, Max payload 21 t.
The OEW difference between a 737-800 and 737-900 is 41,413 - 37,648 kg = 3,765 kg. I would assume a similar difference between a 737-8 and 737-9. A 737-10 will be heavier than a 737-9. I assume that the difference between a 737-8 and 737-10 would be 5 t.
So we have for the 737-10 with one ATC (standard) a MTOW, of 90 t, OEW of 50 t and max payload about 24 t. Range 3300nm. cargo capacity 55,5 m3.
24 payload would leave 16 t for fuel. The weight of the fuel on a 737MAX is 22.282kg with 1 ACT. The 737-10 would be fuel limit to 16 t and could use the max payload for short trips only.
Let us take the standard A321neo with 3 ACT.
MTOW 97 t, OEW 50.1 t, max payload 25.5 t, max fuel (3ACT) 26.450 kg. Cargo volume 50.1 m3 The A321 would also be fuel limited. At max payload it would take 22.4 t of fuel. So the range, it could deliver its slightly higher max payload to, would be considerable more than the 737-10.
Yes the 737-10 would have a slightly larger cargo volume with one ACT against the A321 with three ACT, but remove 2 ACT from the A321neo and you have the space, slightly more payload and more fuel, 22.3 t with one ACT. The A321 is not longer fuel volume limited in that configuration.
Under no operational circumstance I would be able to see an advantage for the 737-10 in regards to cargo.
When we go to the next step, the A321XLR, we see an increase in MTOW to 101 t. The fuel capacity without an ACT 26.9 t.
We do not have an OEW, but the weight is supposed to match the A321neo with 3 ACT, that would mean 50,1 t. Let us say 50,5 t.
That would bring MTOW 101, OEW 50.5, fuel 26.9 t and payload could be 23.6 t. With max payload at 25.5 t, fuel could 25 t.
Cargo volume should be around 54 M3.
This frame matches the 757-200 in max payload over the shorter ranges and surpasses the 757-200 over the longer range..
This frame is still further removed in capabilities from the 737-10.