I hope coinbase adds SegWit compatible sends,receives . If coinbase use Segwit, Bitcoin will be able to process many more transactions per second than it could otherwise, and everyone can expect to be able to pay lower fees on their transactions.
Beyond that, Segwit paves the way for other powerful Bitcoin innovations (like Schnorr signatures, scripting improvements, and second layers like the Lightning Network), so if Coinbase implements it, they are a lot more "future-ready" than they would be without it.