My 2015 15" MBP is also still kickin, is/was an absolutely fabulous unit. Was my work machine for 3-4 years, and now another almost-6 years as my personal laptop. My personal use case is obviously not very demanding but it's only now starting to really show its age.

I also have a M1 from work that is absolutely wonderful, but I think it's time for me to upgrade the 2015 with one of these new M4s.

The longevity of Macbooks is insanely good.