Stokowski, Bernstein, Karajan, Toscanini, and Williams (conducting his own music)
In contrast to Stravinsky, Williams' works in a complete form have been recorded and conducted nearly exclusively by him. To lose these recordings is to lose the intended interpretations conducted within days or weeks from when the music was written, performed by top form London Symphony Orchestra or elite gig musicians for whom the athletics in it were intended.
Stokowski, Bernstein, Karajan, and Toscanini put together should save a significant chunk of the main repertoire in at least very good interpretations.