This makes no sense. Airlines hate canceling flights: they already maximize the hell out of their fleet utilization, so there's very little space capacity in the system and the knock-on effects of having to find new seats for 100+ pax per cancelled flight are massive. Pricing power has indeed gone up, but not in the airlines' favor: for example, Airbus can now charge what it wants for the A320 (the only viable 737 competitor) and wages for qualified A320 pilots are skyrocketing.

Yes, the situation is even better for $Manufacturer where $Manufacturer != Boeing.

But airlines aren't suddenly cancelling flights. They're looking at their schedule and consolidating whatever they can. And charging more for the remaining seats.

And the value of the aircraft they already own just went up.

I've also seen some airlines downgauge turbojets to Q400s, which is slower but saves a ton on fuel.

Routes that needed to run X times per day to be competitive (because people want flexibility in departure and return times) can now be consolidated into X minus Y flights with the same number of passengers.

It's 2019, airlines have automated processes to rebook when a flight is cancelled.

And upstart airlines trying to build their fleets couldn't.

Still not buying it. The value of the Maxes they own sitting on the tarmac has plummeted and all the capital they consumed now has a big fat zero ROI (negative, really, because they still need maintenance and interest payments). If airline X has to reduce flights because they can't fly them, and airline Y doesn't, those flexibility-demanding, well-paying business pax will migrate to Y, and it's Y who will reap the most gains from the sudden reduction in competition.

And automated rebooking is a fantasy. Sure, the airline will try to default you onto some other connection, but I've always ended up talking to a human afterwards and picking out a better alternative.