It's happening to at least one airshow over here in the colonies too. The Alliance (Fort Worth) airshow has been reduced to one day, in part to be more 'sustainable'.
Formerly great event continues to go downhill due to rising cost of attendance (parking/admission charge is $80 this year!), increasing noise complaints by the new neighbors (the airport was here first and hard to miss), and operational constraints (Amazon is not willing to pause operations for more than a couple hours).
Glad I was able to attend in the days when there was actually a static display and an entire day of aerial acts.
*As I'm typing this, I wonder if they mean sustainable from an environmental perspective or from their financial perspective... or maybe both.