The 2020 Airshow was cancelled due to Covid-19. The New Zealand Government advised that anyone coming in from overseas would have to self-isolate for two weeks so any pilot or tour group would be affected. The Trustees cancelled the Airshow three days prior to the country going into lockdown.
Some of the aircraft that would have been at the Airshow included:
Stratofortress B-52 bomber from USAF
RNZAF all types
See here for the list of aircraft 2020 that were coming to the 2020 Airshow - many of these will be at Warbirds Over Wanaka 2022.