Major airlines are back to a situation faced by startups... namely they have to run heavily loss-making flights at near empty for maybe a month... once people see them operating reliably with no major issues, they will start booking again. Of course if an airline messes around too much in that 1 month period, consumer confidence will disappear
Difficult balancing act for airlines as to how fast to add back capacity, when there is very little historic or proxy data showing demand in a post-pandemic scenario