I don't think they retired them all; just parked them. This airport in Victorville is cheaper than leaving them at any commercial airport. In normal times it has lots of aircraft parked there, a lot of them unpainted, waiting to be subbed in as a lease for when a branded airplane is offline for repairs. It's an overflow lot for large aircraft; that's this airport's business model.

... Or maybe the world gov'ts all needed some alone time in the skies to welcome the aliens from their asteroid ships.