I wonder if they could retire Elwood Downey's callsign like they retire numbers in baseball to show our collective gratitude for his contributions to our hobby.
The best existing ways to preserve the legacy of a callsign: 1. have an amateur operator in the Downey family "adopt" the call, or 2. have a club purposefully take the callsign once it is available to reissue. I do not believe the FCC will "retire" a callsign for legacy purposes unless such a request comes through some serious political channels, and I'm not sure that has ever happened. One point of discussion - is the desire to never hear the call again, or is it to let the call live on in his memory? Perhaps the idea is not to let the call slip into some unsuspecting ham's license sometime in the future. That's happened with some notoriously bad callsigns, too - if anything, the FCC should put a lengthy hold on reissuing calls that have had records of enforcement activities.
On a whim, I looked up the late Sen. Barry Goldwater's call, K7UGA, and found it in use by a club called the Central Arizona DX Association. I think that's a great example of paying homage to a worthy SK ham. Goldwater was, of course, a senator and presidential candidate from Arizona. Unsilencing the key.