Of course the sound of a banjo will change as the various parts age in various ways. The question is whether the changes will be audible. I've played my latest banjo for a number of years and I don't hear any difference. I like the same things about its sound today as I did the day I bought it. However, that might say more about me and my hearing than about the banjo.

Also, a presupposition of the search for the bluegrass banjo grail (prewar Gibson Mastertone) is that prewar Gibson Mastertones HAVEN'T changed significantly.