This is by far the most interesting sales campaign going, IMO. We've seen reports citing "insiders" that Boeing had lost and a deal would be announced at FIA, but it appears still to be in play. https://www.reuters.com/article/us-aira ... SKBN1K71V3
IMO this A339 vs. 78X issue, if viewed in isolation, is a no-brainer for the 78X. I don't have access to any published analyses of 78X vs. A339, but analyses of A339 vs. 789 converge at 2-3% variable operating cost advantage for 789 over a 3000nm mission (8ab A330). If we assume that 78X has ~14% more capacity than 789, and that the extra capacity's variable trip cost is ~50% of capacity delta, then 78X should have ~7% lower variable cost per seat than A339 and only ~7% higher trip cost. If we move A339 to 9ab, variable cost per seat should be about equal.
Boeing seems able now to match A339's price, which means 78X should be beat to match the price-per-seat of A339 (incremental cost of 78X production over 789 should be low-single-digits).
Folks in this thread have discussed whether Air Asia X can charge a premium for 78X seating, but that's not even necessary, IMO:
AAX seats "only" 377 pax in its A333's; 15% more seats would mean 434 seats in 78X - just short of max seating capacity (440).
And that's assuming an equal mix of J/Y and retention of 32in pitch in the 78X. Most likely, AAX would slightly shrink seat pitch (31in) and slightly increase the J/Y ratio. The combination of these two should keep average yields approximately equal.
So 78X should have slightly better cost/seat than even a 9ab A339; trip cost should be within a few %. Viewed in isolation, 78X seems like the far better A333 successor than A339.
Against these arguments for the 78X are (1) transition costs from A330 to 787, (2) capacity risk and yield dilution, and (3) Airbus-AirAsia strategic relationship.
Re (1), these are often overstated. Pilot costs in total are low-single-digits % of total widebody operating cost. If transition costs (training and/or hiring) are 10% of lifetime pilot costs then we're talking a fraction of a percent of lifetime total costs.
Re (2), AAX's yield curve is likely very flat. If they want to expand in Europe (they do) and capture more share in Australia/NZ, then they will undoubtedly be constrained by a reputation for the narrowest seats in the world. Non-Asians are fatter and have different social conventions about personal space; I just can't see many fat Germans (they approach us Americans in average girth) tolerating 16in seats for a 10hr flight. So in sum, the capacity/yield issues are ambiguous at best and could reasonably be seen as favoring 787.
Re (3) - this is kicker IMO. A321NEO is plainly the best narrowbody product available, especially for high-density LCC's like AirAsia. Airbus' ability to bundle A321 with A330 will probably result in keeping this deal away from Boeing.
But this doesn't come free. Airbus will have to give some on the A321 terms to keep the A330NEO alive. Is that a good long-term strategy for Airbus? I have my doubts. Given Boeing's rapid acceleration and improvement of 787 production, the A330NEO seems like a mistake. The 78X is a better A333 replacement for all but capacity-sensitive 9ab operators. Airbus can keep the NEO alive via strategic bundling, but that basically means "spending" some A321neo profits on A330neo.