Coinbase  exchange is nearly similar to other exchanges, so they may some day add Ripple because of its high volume during pump and dumps so they can make more money but there is also the fact that Ripple is centralized and they can close your accounts if they want to. so if Ripple labs finds Coinbase not to their liking they can shut them down and make all their Ripple balances go to zero just like that. and i would defiantely hate to see coin base manupulation like bitcoincash and expect the same way to happen with ripple so please stay away from these rumors