Someone else mentioned "Just have a Ring of Fame" and give props that way! There are only so many numbers to wear. lol
Give me a Ring of Honor and maybe even a "Ring of Fame" Wing in the stadium. You could display all kinds of memorabilia, pictures and more. You could even have events in the Wing and bring in some of those "stars" for additional recognition! IMO, the fans would love it just as much if not more than retiring a players number.
I am sure they could find a way to make some $$$ off it too!

#HelmetHornsMatter
“Well, the color is good, I like the metallic blue,” Youngblood recently said while laughing, via NFL Journal. “The horn is terrible. It looks like a ‘C.’ When I first saw it on the logo I honestly thought it was a Charger logo.
“Now when I see it on the helmet, it just isn’t a ram horn. There is no distinct curl like a mature ram horn. I don’t know how the Rams could get that wrong. That is your symbol and it has been for what? Seventy years or more? Longer than I have been alive? It’s just not us, it’s not the Rams.”---Mr. Ram Jack Youngblood