There are probably so many replacement parts that exist for iPhone 4,5, and SE series, Apple could easily create an updated low-cost iOS hardware offering, but

There are probably so many replacement parts that exist for iPhone 4,5, and SE series, Apple could easily create an updated low-cost iOS hardware offering, but that won’t be until they fully embrace being a services company. Their lower-end offerings would be ‘lowcost’ thin-clients.