In looking at the specs of the 2018 mini, I notice the absence of optical audio. I use optical to connect my current mini to the stereo and would hate to lose it. Yes, i could use HDMI, but my TV panel doesn't have ARC, so I can't drive it as a monitor AND have audio at the same time.
https://www.apple.com/mac-mini/specs/
https://www.apple.com/mac-mini/specs/