Great question Eberhard!
I often lamented, in my 40's, that work cut too much into my free time for pursuing my real passions (and I had a pretty stimulating job as an environmental consultant): family, playing CG, sailing, or fly fishing. Obviously we have more time to pursue these things. We also I think have a different perspective of time. If someone HAD told me at age 12 that I just needed to put in the 10 years or whatever (and maybe someone did), I can hear myself saying, "Holy crap, no way! I can learn theee chords and play any tune on the top 40."
We should have lifelong passions that are physically and intellectually stimulating, and expansive and evergreen. Music is perfect. If I can't play I can write. If I can't write I can listen. The 10,000 hour goal is not about achieving someone's opinion about perfection or mastery, it is about pursuing a goal and maintaining the "beginners mind." That keeps us "young."