There are other threads for medical. This is about airlines. My crystal ball is just that but my thoughts are
1 lockdowns will be much longer than we think with clusters on releasing them. It may be Fall 2021 before we have a vaccine and manufacture enough - if the US grabs it all other countries will be infected and infect unvaccinated Americans....
2 Many businesses can bounce back. Banking. Restaurants and other small businesses that just start again. there will be loads of landlords trying to rent restaurant premises
3 After lockdown many of us will question business travel when we can avoid being treated like imbeciles in steel tubes. global warming will become an even bigger panic, and to be fair it will be because the scientists who will resolve it are locked down and lockdown will result in a massive population explosion which is the real cause. so demand for aviation will be weak.
4 There will be massive government debt. austerity will return and taxes rise. This will stifle risk taking and new business ventures, affecting business travel. Increased taxation reduces leisure travel.
5 Bringing machinery and personnel back on line is problematic. Aircraft wont have flown. Pilots wont have currency. Key workers in the training and command chains will no longer be with us due to Covid 19 or retirement and lack of recruitment.
Of course for those in the industry there may be a move back to the good old days. Salaries and terms and conditions of service may improve with shortages, less passengers may mean they are treated with respect etc etc
I shall look at this post sometime next year and see if any prediction is correct.