Sequestration is the cause - USAF participation in public events was cut in March 2013 for the remainder of the FY:
Budget Cuts Ground USAF Thunderbirds And Eliminates Support To Air Shows | Ottawa Citizen
MCAS Yuma still managed to put on a very worthwhile event with USMC assets, including MV-22, AV-8B, F-5E and privately owned classic fighters flying and all current inventory types in the static display including F-35B, UH-1Y and AH-1Z.
However, Aviation Nation 2013 at Nellis AFB, normally an excellent free show with flawless organization from which RIAT could learn a lot (free parking at the Speedway and a fleet of 50+ x 50-PAX coaches for shuttle - no queues to approach and park - on the base within 15 minutes of parking including security check and shuttle) is cancelled. As Las Vegas loses about $18M in business due to the cancellation, a consortium of business owners was trying to come up with some kind of sponsorship deal but it was obvious from the outset that the DoD bureaucracy could never be overcome in the 8 months available.