Sales numbers are down, weak, non-existent, whatever because there is basically no advertising or marketing, for the AMF brand of bowling balls.
A few years ago Motiv was a niche brand with not a whole lot of interest compared to the other brands. Then Motiv started to advertise, put it's product in pro shops (that's how I bought my first Motiv ball), signed some very good players, sprung for PBA product registration and low and behold Motiv is now considered a company who's balls can compete with anyone's.
The formula exists, the AMF iconic brand can be resurrected but, the powers to be have to want to do it. Apparently, they don't.
I will continue to buy AMF balls. In my opinion, the AMF Solar Flare (2013/14) was an awesome pearl ball for medium conditions (one of the best I ever owned), to bad so few apparently either knew about it or purchased one. And from what I read here on BR, a number of people love the AMF brand of balls. Try one, you may like it.