I had thought Tahoe was the first version to drop Intel CPU support, but it looks like it will be the last version to still support Intel Macs.

Two of the latest Intel MacBooks, and the last Intel iMac, so technically, yes, there’s still some Intel support in there. My 2019 iMac is one version too old.

does not support 2018 Mac mini

Apple have always seemed to drop support for hardware after 5-7 years, and then it's just a question of the last supported OS becoming itself unsupported too. My early 2015 Macbook Pro (new in April 2015) got as far as macOS Monterey (released October 2021) - and they stopped updating that in October 2024.

(I'm not digging through Wikipedia to double check but my previous 2 Macbooks Pro felt like they lasted about as long.)

It'll be interesting to see if they change this with the (presumably cleaner slate) Apple Silicon-based hardware.