It will never happen. It would only add more nanniness to the nanny state, as well as create nightmares for retailers and their normal paying customers. Existing stamp quotas in dollars work about as well as anything to encourage frugality. USDA surveys from the Bush II era show that stamp recipients include fewer, not more junk foods in their food orders than paying customers do.
People who use food stamps are already by definition Nanny Staters. If they don’t like being unable to buy meat with their stamps, then they should get off the stamps. But yes, I am aware that changing the rules doesn’t mean changing behavior. Fraudsters will always find a way.