I doubt it's anything sinister — I think it's simple economics. I'm hearing different things, but the common thread is continuity of supply for the relatively low quantities being ordered. As DJs we might love them, but I doubt that Shure can order the quantities of parts to make them viable anymore. It could also be that the tooling needs renewing, which is a hugely expensive cost to recoup in a stinking market. Compared to the rest of their business, carts are just the smallest of blips on their balance sheet, and probably not worth them continuing with.