It wouldn't be crazy for them to offer a mini only every several generations. If the problem is that there isn't enough demand to justify design and tooling, it would make sense to let demand grow for 5-6 years, then release a new mini that all small phone lovers will buy.
Yup, Apple still makes a new iPad mini every 3-4 years, despite it being clearly worse on paper than the mainline iPad. But the last version was mostly a spec bump.