You know, that's a fair point. I think there's a great argument to be made that FOSS software in particular is essentially post scarcity.
I'm not sure I'd say we're "post scarcity" for books and other digital goods though. Sure, we have all the books written until now, but I think there's an argument to be made that a huge part of the utility of books is that they are produced in near-real-time to discuss, address, and reflect thecurrent state of society. As our society grows and changes, books featuring the issues of the days will always be desired. This falls into the "trends" category you mentioned, but my point is more that I think it's larger than you described.
I'm not sure I'd say we're "post scarcity" for books and other digital goods though. Sure, we have all the books written until now, but I think there's an argument to be made that a huge part of the utility of books is that they are produced in near-real-time to discuss, address, and reflect thecurrent state of society. As our society grows and changes, books featuring the issues of the days will always be desired. This falls into the "trends" category you mentioned, but my point is more that I think it's larger than you described.