Historically speaking the great American boxers have come from the ethnic/immigrant groups at the bottom of the socio-economic ladder. These communities have seen a large decline in the number of gyms available to them. The lack of gyms is a chicken or egg issue. Did the gyms decline due to a lack of interest in boxing or did the lack of interest in boxing happen due to the decline of gyms. Baseball has also had a decline in American minority participation due to the number of participants needed, equipment availability and lack of facilities. I'd be willing to make a hefty wager that just about every low-income housing area in the U.S. has some sort of basketball court hence inner city black kids simply need a ball and 2-10 guys to get a game going. This is pretty similar to my experience in third world countries where a group of barefoot children kick a makeshift ball around a dirt patch. As the quality of life has improved in the U.S. along with more athletic opportunities (regardless of the international interest in them) its not hard to see why someone would choose a sport that doesn't involve them being punched in the face. Barring another Tyson or SRL that grabs the collective U.S. interest and/or another influx of immigrants with a cultural history of boxing I think the current status of American boxing is here to stay.