I am with Calypso.
There are also thousands of old captains worldwide that either took pre-retirements with good packages (from major airlines) and won't come back or the ones that just had enough and won't come back (furloughed in middle east or asia) because they made enough cash and don't want to dislocate again into an expat life.
The training bottleneck will be in a way as we have never seen before.
All experience shows a massive and super-quick rebound of the customers as soon as routes open up, something the airline leaders have not foreseen and have not planned for.
It is not accidential that Emirates is already inviting applications from pilots who have not worked for Emirates before. I would guess they had to learn quickly that a significant part of their forloughed or fired pilots did not show any interest in returning after Emirates invited them to express interest for a return.
Training departments are usually dimensioned for a rough staff turnover in the region of 3% a year. We are talking more than tripple that.