Billy Abbott (O'Melveny & Myers, Silicon Valley), The Anything Asset: The Tax Classification of Cryptocurrency, NFTs, DAOs and Other Digital Assets, 26 Chap. L. Rev. 459 (2023):

The first question for any tax practitioner looking at a digital asset will be this: What is it? Given the flexibility of digital assets as evidenced by their already varied use, in a sense, a digital asset can be almost anything. Although tax advisors are used to applying old rules to classify new assets, the versatility of digital assets will stretch that approach and change the practice of tax law. This Article explores the interesting and challenging issue of classifying digital assets: first, through specifically considering the tax classification of common categories of digital assets–cryptocurrency, DAOs and NFTS–and second, by asking whether any or all of those assets can be classified as "securities" or "commodities" under a few key provisions of the Code.

Conclusion
The classification issues described in this Article merely scratch the surface of thise that will arise when tax advisors seek to apply to existing tax law to the wide variety of digital assets out  there–not to mention those that have yet to be invented. But classification has always been a mainstay of tax practice. The addition of digital assets to the economy will impact the way tax law is practiced to be sure, but it will also only be the latest in a long history of challenges faced by advisors confronting novel situations.