No way. Commercial air travel is ready for a 10 year slowdown.

The main profit center for commercial air travel was businessmen going places, not too concerned how much flights would cost.

Now business meetings happen by video conference. Flying round the world for a 3 hour meeting will never be big again.

TBH, I fully expect that by the end of this year our company will resume sending management on two-week excursions every six months to Hyderabad.

Now we know how to leverage video conferencing for meetings, and we are convinced more than ever of the limitations given current technology.

In fairness, most business travel is not flying around the world for a 3 hour meeting. I do expect events, roadshows, series of customer meetings, etc. to come back--albeit probably gradually and perhaps not reaching prior levels.

"Commercial air travel is ready for a 10 year slowdown."

You're not really offering any evidence, just speculation. The actions of the major airlines suggest an expansion, not a retraction.

Are they expanding... Or are they switching towards more fuel efficient planes with the expectation that it won't be long before countries start restricting flights that produce too much CO2?

Airplanes have a lifespan. Janky "third world" countries will let you fly a plane that should have been scrapped, but the big airlines in major countries scrap their old planes at the end of life to ensure flying is safe. Getting more fuel efficient planes is a side effect (and with the cost of fuel one they are excited to get)

"never again" are such big words. Let's not assume short to mid-term shocks will automatically translate into long-term changes.