About the asymptotic to zero assertion (I'm not disagreeing with the assertion, simply expanding it's applicability, or not): why only confined to software (free or not)?
I've believed for a long time, and the data is certainly bearing this out, that ANYTHING on the Internet eventually follows the asymptotic to zero value assertion. Certainly this is true for music downloads (although there appears to be a hiccup in this curve right now, but it will pass).
One must work VERY hard to fight this trend, but in the end a certain kind of 'entropy' wins out. In this case 'entropy' is the increase of value of 'stuff' (shared knowledge in the case of OSS) in a closed system (the Internet) that cannot be monetized by the 'originator' of said 'stuff'.