This is almost an interesting pole. So many things impact performance over the years.
I think ski selection and tuning are way down in the noise as compared with regular access to a course, injuries, proper fitness and coaching. I've been pretty serious about skiing for the last about 20 years and have improved over time, although PBs come slower as you get better. At some point your ability to continue improving runs into the physical limitations of age. I'm pretty sure I'm close to that point now at 60.