Coinbase is issuing tax statements for tax year 2017, a.k.a. 1099-Ks. The assumption you can make is that Coinbase has been tracking the trades since the day they started, and have that data.

I don't know what to make of the fact that neither Coinbase, nor GDAX, required my Social Security Number. I volunteered my Date of Birth to Coinbase for some extra level of security, and I did have to send a photocopy of my Driver's License to GDAX. The question I have is can Coinbase issue a 1099-K without the Social Security Number?

Crypto was always property for IRS income tax purposes. The IRS clarified this in 2014, not 2017 as the author states. If you filed a tax return for tax year 2012 with cryptocurrency trades, you would still treat the crypto as property.

The new tax law for 2018 made it crystal clear that one cannot do a 1031 Exchange of cryptocurrencies starting with 2018. Whether one can do a 1031 prior to 2018 is hotly debated. The BIG CHANGE that people refer to is the clarification that no way can you do a 1031 starting with 2018.