I think the author's conclusion is true if you allow for several unstated assumptions. Also this conclusion applies only to nfts with potentially infinite supp

I think the author's conclusion is true if you allow for several unstated assumptions. Also this conclusion applies only to nfts with potentially infinite supply, NOT "art". The first assumption is that the transaction costs of buying and selling a copy of an album or ebook nft will be zero (including hassle and book-keeping costs). The second assumption is that there is infinite supply, forever, at some ceiling price (e.g. someone will always sell you a "new" beatles album nft for $10). The third is that there are no "sinks", e.g. the copies are never consumed or degraded by loss, incompatibility, releases of better quality, etc. Also, the argument requires the copies are more or less "fungible". But I think yeah, logically, if I can buy a new X at $10 which lasts forever and is infinitely tradeable with zero transaction costs, eventually the secondary market price of X would tend towards zero. Effectively the whole world would be purchasing floating licenses until supply > demand and eventually that condition is permanent. In practice, owners of copyrighted works have a lot of ways to avoid this situation and I expect they will act to license their works in ways that avoid this.