Is it not true that for ranges a 321xlr can do, the cost per seat is much less than a 330neo or 787.
Not necessarily. Tests done in 2016 compared an 321LR to a 330neo did not show an advantage per seat. I don't think the XLR will have better numbers than the LR.
Airbus A321NeoLR : 154 [email protected]
,300 km burned 2.99 kg/km
Airbus A330neo-900 : 310 [email protected]
,200 km burned 6.00 kg/km
So twice as many seats burned fuel at twice the rate. So on a per seat basis they were the same.
There are no list prices published for the LR and XLR versions, but we can guess that the A330neo is roughly twice the price of the A321neo
A321neo $129.5 million
A330-900 (neo) $296.4 million
So there is no advantage in the amortized cost of the jet purchase (or the lease price).
So if you are not utilizing the extra 2500 nmi of range
the only real advantage of the larger jet is if you are in a slot controlled airport, or you have some savings in personnel cost (pilots and flight attendants). Basically the flexibility provided by the smaller jet should win for amost situations.
Someone stated that Delta would replace any widebodies with A321XLRs, just the B752s. I disagree, as I think they will be more flexible than the older smaller widebodies.56 Boeing 767-300 23.6 (years) potential replacement with XLR
11 Airbus A330-200 14.7
31 Airbus A330-300 10.9
4 Airbus A330-900 0.4
13 Airbus A350 XWB 1.8
21 Boeing 767-400 19.0
18 Boeing 777 14.8
Personally, I could imagine shrinking to 100 A33-900 and A350s from their current 154 widebodies with A321XLR making up the difference, bu it would take 12-15 years.