As I am sure many of you guys know, Coinbase has undergone two rounds of maintenance. The reason given for this is to improve the Coinbase experience for "millions of additional customers". Coinbase is a very large entity in the cryptosphere and having to take down all systems related to transactions must be with a good reason. There has been speculation about Coinbase adding additional coins in order to expand its customer base and that line that was in the maintenance message may point in that direction. If there were coins to be added to Coinbase, Ripple, Tron, EOS and Monero are in my opinion the biggest candidates .