So what could be behind the story? I see two possible scenarios:
1. Absolutely nothing! Maybe Mr. Foster, President of Air Astana, just wants to test the waters and hopes that other airline CEO’s and influential people join the discussion, raising the pressure for Boeing – and for Airbus, which would have to react once Boeing would announce to do something.
2. Boeing sees that the B737MAX-9 is inferior to the A321neo and uses Mr. Foster to tell airlines around the world not to buy anymore A321neo as a better aircraft could be “just around the corner”.
I think it is more likely that it it something like scenario 1. Investing billions of dollars in such a small niche and, as Air Astana’s CEO suggested, to announce the development now with an EIS that could not be before the middle of the next decade (see Scott Hamiltons comments here) just would not make sense. Sales for the B737MAX-9 would probably suffer more than for the A321neo, as Boeing’s customer base will be more willing to wait as the customer base of Airbus, which is easier for Airbus to keep in their camp.
Also, as Scott pointed out, it would be a family of aircraft, replacing the B737MAX-8, -9 and the B757-200 (for sure not the B737MAX-7). With the 2000+ sales of the B737MAX one can calculate that the production horizon reaches until almost 2023 now. So why prevent further sales of the B737MAX now by announcing a successor too soon? It just won’t happen! Not now!