But you can simply resize .32-20 brass into .25-20, so any old rifle in .25-20 does not have to be retired.
Both Colt and S&W stopped manufacture of .32-20 revolvers before WWII, so there was really no market niche for this caliber by that time. In fact the only two viable current markets for the .32-20 are those who just like to shoot old guns chambered in oddball calibers (I am one of them), and Cowboy Action shooters (I used to be one of those also). .32-20 rifles and revolvers are fairly popular among the CAS crowd. .32-20 guns are nothing a hunter should use for anything other than small game, and even so, there are much better calibers available for small game. But I am sure that many thousands of deer have fallen to .32-20s. Likewise, the .32-20 is not a good personal defense caliber in comparison to many others on the market, but it would probably work OK if nothing better was available.