I agree that S21 will be difficult. At least with the S20 season just gone people will have been booking for this right up to March and maybe beyond as initially a lot of people thought this would be over in a few months. So despite the massive amount of refunds airlines still had some money in the bank. How many people will be booking for S21? I would suggest a few are but it won't be many so airlines simply aren't getting any money coming in, as many rely on money in the bank for future travel to keep going.
If IAG falls how many airlines will go before it as they are one of the stronger ones?