n911 points out that the new tax law specifically disallows crypto-crypto transactions from like-kind treatment starting in 2018. This is actually good news for me, because it suggests that the IRS won't fight it for prior years and I wasn't planning to claim like-kind in 2017. So now I will claim like-kind for the 2017 tax year which will save me a lot.

Note if you do this you still have to file IRS form 8824.

Most crypto traders ignore the issues entirely. This will cost many a lot of money, time, and trouble. The IRS will catch up with those who don't declare their gains - there is a lot of potential revenue in there for them.