Nope, it will never happen, and i will just explain you why they are never going to add ripple on their platform:
Coinbase does not allow Centralized coins, and do you really think that they are going to list ripple? It is controlled & manipuled specially from banks.
A LOT of people have been wondering when/if coinbase will add ripple. Any thoughts?
No, they will never do it, and not even monero. They listed ethereum in there because it really needed to be added in there, but it does not means that they will add the top 10 from coinmarketcap in there.
Eventually they'll add ripple. Then others like Monero. Most likely Q1 2018.
And in the first quarter of the next year? How do you have that information? are you from the NSA or the CIA? Haha, came on.
It's an educated guess. There's a lot of demand for Ripple.
I mean cmon....They added Bitcoin Cash
what makes you think they wont add ripple onto GDAX..