Based on recent press in the UK, there seems to be a decrease in the public's overall confidence in some specific airports and airlines.
If you fly a particular airline at least a few times per year, and you can buy a ticket for which change of date+route is available at moderate cost.... what is to stop you from buying in advance multiple tickets for a route (i.e. on different flights on the same day), waiting to see what gets cancelled between purchase date and flight date, paying the modest change fee if necessary to defer any tickets you can't use and thus having a much higher certainty of reaching your destination ?
It seems to me as if the option on being able to change a ticket has suddenly become a lot more valuable... with the consequence that (based on historical no-show data) an airline that thought the flight was fully booked 24 hours in advance, will suddenly find itself with a lot of empty seats 3 hours before departure time