https://www.techradar.com/news/mac-mini-2018-release-date-news-and-rumors

It’s been almost four years since we last saw a major update to the Mac mini, and while some people have taken Apple's silence to mean we won't ever see a follow up, we still hope that we could indeed see a new Mac mini in 2018.

The fact that a new Mac mini was not released in 2017 disappointed many people, but Apple CEO Tim Cook himself has reiterated Apple’s support of the Mac mini, so there’s hope we’ll see it this year.