I feel like BS is taking over because people come to dance to create connections. Salsa music is hard to learn. Usual route is to take classes where teachers teach complicated moves (in On1 and On2 thats the route). Its physically challenging. By that time, people get exposed to bachata or zouk and connect to a new bf/gf while dancing bachata/kizomba/zouk. The insistence of having multiple turns in 4 counts is making salsa less popular (and using very fast songs). Also we have to recognize that year after year latin music is changing and there are less and less songs that can be used for salsa dancing.