There has been some news coming out that the US will be changing its considerations for what is exempted as a like-kind exchange of property. In regards to cryptocurrency this could have repercussions to those who trade currencies.
It is looking like Like-Kind Exchanges may soon only pertain to physical real estate investments, and same for same coin/token exchanges.
Please consult with your accountant or tax preparer to learn more about how these changes could effect you in 2018.