People pay even more for the six year old 2012 Mac Mini because it is upgradable and has a quad i7. Apple could easily create a new quad core upgradable mini and the demand for the product would be huge.
Apple managed to put a HEX Core Desktop class CPU in the 2018 Mini and you can upgrade the RAM but not the storage... yeah Apple is gonna sell a ton of these. The 2012 Mini has finally gotten a worth successor.