The answer to this question can be answered if you split the pilot groups into three categories of age, young, middle age and senior.
In the air less crews will be needed because less planes flying which means less pollution as well. we all remember working 90+hours a month and being exhausted from short layovers and not recovering fully from the fatigue. Airlines could reduce the wage bill by reducing flying hours for pilots to 30 hours per month and then replacing them with fresh pilots to fly another 30 hours. What will these pilots do the rest of their time. For the airlines to survive they will be planning new roster program's that will have very little resemblance to precovid operating rosters, and so we enter the world of job sharing!!
In all this drama has anyone even considered the future of the poor ageing B737 and A320's basking in the desert? what future lies for them is obviously early airframe retirement with the engines operating the same as the pilots at 30% rate.
At the last count there were in the region of 39000 Aeroplane which begs another question, does the world need this many in 2021? so if travelling in a large social group of 200,300 people becomes restrictive with no workable vaccine, high risk of disease transmission then perhaps this mode of travel will come to an abrupt and untimely end. The jurrasic period brought the end of large dinosaurs giving way for the smaller species to inherit the earth maybe similar fate awaits the aviation Industry with the advent of smaller personal flying vehicles.
Reading between the lines i would surmise that all the fossil fuel guzzling machinery of today that includes aeroplanes, cars and coal burning power stations have there days numbered.
Is it coincidence that society is being persuaded and mandated to not travel by air, stay at home, and not use their cars, all to avoid the reduction in the worlds oil reserves. We all seen three countries send probes to Mars this Summer, Spacex and Blue Origins having ambitions to terraform other planets and our own Moon. Building spaceships to go to Mars within two years that’s desperation of a dying species, Perhaps Mining asteroids and other planet exploration is not a bad idea after all. If you believe some of the reports published, the world should have run out of oil 10 years ago. But here we are today with some estimates we have another 30 year capacity left.
Coming back on Topic regarding which pilots will still have a job in 2021?
Well I understand that the older group will have retired - early or forced to go as they are not favourably looked upon by airlines due to their experience, higher salaries, more frequent medical intervals and obviously not a good long term investment.
The middle age group are in the best position, they have sufficient experience and will be needed to train the younger third group when airline industry recovers.
The third group if not employed already will get their chance to fly but it will be very competitive and only for the chosen few and certainly not have the financial rewards they expected from pre-COVID days. Some from this group will have come with debts to repay from aviation training.
One thing I haven’t mentioned is crew complement on the flight deck. Normal crew of Pilot and copilot has been the norm since single pilot operation stopped decades ago. But for the future it will be interesting what kind of operating procedures the airlines will adopt, not only to deal with passenger health and safety but on flight crew operation. Perhaps the copilots will be passed over for junior captains flying their right hand seats. Airlines may decide to recruit, fly, and operate with different business objectives and criteria. Here is an article on current recommendation from a leading flight training school.