What's a beer you're nostalgic about that is no longer available? Possibly even one that helped convince you to be a craft beer lover.
One of the first to come to mind for me is Bert Grants Scottish Ale.
Miller Reserve Amber Lager, and Miller Reserve Amber Ale. Both fine beers.
And Coors Winterfest. Plus the beers that AB used to brew...their Marzen, Porter, plus a few others.
All the above are way too busy making Miller Lite, Coors Light, and Bud Light. That's where the demand is.