The Pro Mini will never happen. Best we could realistically hope for is the same design as the latest iPad Air 4 with touch id in the power button. I'd buy one (eventually, since my Mini 4 is still ok).Give me an iPad Mini 6 with the Pro design (and similar specs)
But all the recent rumours suggest it would instead be iPad Air 3 design. So, slightly slimmer bezels but still a home button and a lightning port. I personally don't see a point in such a refresh as it's too similar to existing Mini 5, which performance-wise would remain capable for years to come, having the A12. Just drop the price $100 and be done with it.