Co-operation in business is always more profitable than competition. By rights, Boeing and Airbus should go in cohorts on the super jumbo. That way the risk is halved, as is the start-up capital. And it is just those two issues, risks and capital, that have stopped Boeing from going ahead with a super jumbo of its own.
How many here are aware that arch rivals, GE and Pratt & Whitney, are already in business making a new line of engines?
Nor do I see a reason why such a co-operation on a super jumbo would, or could, be blocked. It would not be an amalgamation of the two companies, but merely a co-operation on one product line. That happens all the time. The US has anti-trust laws but those apply to American companies removing other American competition from a US market. They have no jurisdiction over foreign companies in a global market. And let's face it, Boeing swallowed MD, making Boeing the only manufacturer of commercial airliners in the US. A perfect case for the application of anti-trust laws, but they were not invoked.