A general Google of "Coinbase to add Ripple" turns up a few posts of various sites but also mention of a Change.org petition to add Ripple. Seems an odd way of doing it but hey. I think the main driver for this would be 'why not'. They've proven they're a solid platform for BTC, ETH and LTC. Why not add other coins that are likely to grow, thereby not wasting their time in development and losing them money.
Being on Coinbase is also significant for Ripple. It means greater exposure to a more retail oriented market and access to increased liquidity. For holders of Ripple the sooner those escrowed coins are sold the more the price will increase. They're trying to avoid volatility but that's down to the market in the end.
Price predictions from me:
EoY 2017 - Q1 2018:
Solid support at $0.80, typically trading at around $1, price testing at $1.20
Unless there's optimistic news, like Coinbase, I think the holiday season will see sluggish trading
Pessimistic: Solid support at $1, typically trading at around $1.20, Price testing at $1.30
Optimistic: Jump to solid support at $1.20, trading around $1.50, Price testing at $1.80
If things are optimistic the price will skip up, the market will test new highs and trading volume should increase. We need more buyers to absorb the escrowed coins and a few more partnerships and large customers joining in to convince the watchers.
Pessimistic: Support at $1.50, typically trading up to $2, Price testing at $2.80 seeking $3
Optimistic: Support at $2.50, typically trading up to $3.20, Price testing at $3.60 seeking $4
Q3 is new financial years, summer holiday positivity and enough time to have landed more clients, added exchanges and wallets, brought in a new partner or two and responded to things like EU regulatory noises that BTC etc. can't answer, possible new retail clients looking for something on the rise but not as pricey as BTC and ETH.
Pessimistic: Support at $3, typical trading up to $3.50, price testing stalled at $4 still seeking $4
Optimistic: Support rises to $4.50, typical trading up to $5.50, price testing at $6, seeking $8 to $10
I think if we get good news and progress, also after BTCs amazing year and we break through $5 - they'll be energy around Ripple that will see it rise faster than it has been doing. Ending on a solid support level of $5 is perfectly feasible in my mind. The market trying to strike out towards $10 given it's 'symbolism' in traders minds is a stretch but not impossible.
Now let's see how wrong I can be I general go with a pessimistic view for stocks, but Crypto... heck that's anyone's guess! Just trying to model some thinking.