The mini was the best selling ipad while Apple kept up with updates. Their response to those sales numbers was to not update it further, and year after year, let sales diminish. Eventually they'll be able to point to low sales as reason to discontinue it, but it's entirely a choice they've made regardless of sales. Instead of updating it, or adding Pencil support, they've created several new larger, cheaper ipads and pushed those instead, entirely missing the appeal and utility of the Mini, like everyone else in this thread who thinks a plus sized iPhone is an equivalent device. It is not.
It's somewhat obvious they never looked into how people use minis, and mistakenly regarded the model as the budget ipad, then sought to make more profitable replacements for it that were all-around cheaper to build than a full featured iPad squeezed into the more convenient 7.9" frame. Add it to the Macbook Air, the Macbook Pro 17", the Air Ex/TC, Cinema Display line, etc. The most useful & popular devices Apple built, all on the fire.