A reality check is in order for those who underestimate the difficulty of getting this many people back on board. Many of those who will hopefully be brought back into the game in the coming year will have spent anywhere between 18 and 30 months on the ground, often out of a job and hence not entitled to any recurrent training. At best, they will have their type rating and medical; everything else will have lapsed. Think all the courses like CRM, Dangerous goods, Fatigue risk management etc. Even their Crew IDs will likely no longer be good - and those are not easy to obtain in many countries. There's more than one place where a bottleneck can form. Even if we assume excellent availability of ground courses and sim slots, what about line training and checking? There are only that many trainers in an airline (and not all of them are current themselves, to begin with). It will be a massive effort, taking anywhere between a few weeks for a small operation with a handful of aircraft and many months for the large companies with dozens of aircraft.