I was flying in Mar (Friday 13th), Sept, Oct, Nov, Dec 20, Jan and Mar 21. Even transatlatic. It is possible. Domestic flights more full than normally. Long haul do not bother to buy business or higher class, mine were empty.
The flights however are far from normal. Sane people will avoid this for vacation. Stress is incredible. The paperwork needed is just rising, last time i needed 8 papers. Nobody can give 100% accurate info. Even at the airport the crew is usually not well informed. I had to use all soft skills, doctor some documents, after the original ones that were supposed to be ok, were not ok for the health-nazi 20years old medical-student-b1tch who was backed by a handsome soldier with a machine gun "this is not correct sire and actually I do not care what you were said by someone on helpline". Once I waited 8 days until PCR test was possible in a city where I definitely did not want to be.
So my advice is to avoid international flights if you can. In fact that is their goal and it works flawlessly. Who needs to fly - he probably can, but substract 5 years of your life for each leg.
Flying will never get to the norm. Am I insane to think that after 9/11 it never returned to the norm? Like throwing away my water and miniscrewdriver for mobile phone? Is normal that some woman needs to steal my 3x4 cm pebblestone at securitycheck? Is normal that there are dogs in Amsterdam that are trained to sniff cash? Is normal that my checked baggage was opened, everything fragile like marmelade was unsealed, then it was thrown inside, so I had to wear my underwear with a mix of strawberries and apricots? Is normal that I am always in stress whether I can taky my walking sticks to the handbaggage etc?
Ok, I am insane so yes, things are going to be normal soon, in the same direction as they were until now. So prepare for the rectal PCR tests or that some random strangers will have access to your medical records. Prepare for denied boardings. Prepare for limited use of toilets. Prepare not just for wearing facemasks, but for wearing respirators. Prepare that if your nose will not be 100% covered you will get the last warning from friendly steward. Prepare for invitation on plane - no s*** I heard that - "whoever will not comply with rules will be reported and police will be waiting at final destination". Forget that you maybe need to breathe during 14 hours flight in the respirator with valve - denied. Prepare on short haul flights that you can not get/buy even a glass of water to water your dry throat. Etc, etc, etc.
If you talk to God, you are praying; If God talks to you, you have schizophrenia.