Personally I would LOVE to see Bitmaintech or BitFury sell prev gen chips after new ones come out. I mean why not??? They should be almost pure profit considering all the production steps and setup costs have been paid for...
Because the cost of printing another new round of old chips is more than the chips can sell for. They can print a round of newer chips for almost the same price, and they are better chips. In this hyper-inflation market, the cheapest wins. Even at an inflated cost.
Even the new chips are barely turning a profit. Why make more of the old chips at a loss?