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.