I got my own clue that Coinbase may be adding ripple soon. When I sent money from Coinbase to my bank (in the US, Citibank) this October, the money showed up the next day. But when I did the same this December, I noticed the money appeared in my bank account same day, almost immediately. So I am thinking, may be Coinbase is now using ripple for it's operations. If yes, then it makes it very likely that they will add it to their trading portfolio soon. Do you think I have a point? You can test it, send money from Coinbase to your bank. It's crazy fast.