thanks for all of the extra detail, very interesting on the third tank (from 47K gallons to 53K gallons of fuel) not being ordered by any airline.

The 777-8 does not arrive until 2021. That is three-four years after entry into service of the 359ULR. The projected range (8690nm) is shorter, and the plane is much bigger (it is 20' longer than a 772, and 13' shorter than a 77W), think seating approx 356 vs. the 234 on DL's A359. The 777-8 is also likely to have compromised fuel burn as a shrink (think 358, 788, 762, now 772) and e.g. LH which ordered the shorter range 779 said it would have similar per/seat performance to the A359 and notably did not order the 778. The orders to date (53 -8, 273 -9) are not indicating a lot of faith in the performance of the -8 model, with carriers with ULR flights (CX, SQ, ANA skipping the -8 version in favor of the -9 version).

Look, Boeing was trying to fill a whole in its line up, but I don't think the economics are there, and I especially don't think that a very large (seating 356 or so) aircraft will work on ULR. You need higher value O/D traffic to support the higher costs of these types of fights, and I don't think an airline - any airline - can fill up this large of an aircraft without a lot of discounted connecting traffic. So far only the ME3 have bought it, and my guess is that they are ultimately the only airlines that buy it, with all others, outside of "fleet commonality" purchases going with the much smaller A359ULR