Are you unaware of what the latest Intel low power chips are capable of? They blow the 2012 Mini clean out of the water. They can do full smooth 4K @ 60hz while doing all the real work you need them to. Look st the NUC boxes. They stomp all over the Mini.
It's not just the u series mobile chips in the latest NUCs. Take mini-STX boards. They allow a case nearly as small as a Mini, while using a cheap standardized board, instead of the custom stuff Apple always does. You can pair that with a cheap Pentium g4560 (s series, $64 list, more right now because of demand), and that's literally faster than ANY of the 2014 Minis. That's not to mention .265 support, 4K/60Hz, usb-c, etc, etc