Level 10

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There are still many things that are unclear about this area since there are no regulations, etc. and don't expect any for quite some time.
I think most commentators (at least the ones I tend to follow) agreed that the exchange of one cryptocurrency for another was a taxable event even before your noted change.  It just makes sense and follows the spirit of IRS notice 2014-21.   Attached is just one article:
<a rel="nofollow" target="_blank" href="https://www.thetaxadviser.com/newsletters/2017/apr/cryptocurrency-taxes.html">https://www.thetaxadvi...>
*A reminder that posts in a forum such as this do not constitute tax advice.*