In the discussion on Twitter that followed the announcement, Armstrong also stated that Coinbase will not be using Bitcoin Classic as it’s sole means of block confirmation:
“we run many node types, including [Bitcoin Classic], good idea to clarify!”
He goes on to make it clear that regardless of Coinbase adoption, users’ BTC will be valid on all implementations – a rare but much-needed statement of fact in the turbid waters of the current block size infighting among the Bitcoin community. Regardless, the response to the announcement leans toward the negative from Twitter and Coinbase users.
http://bitcoinist.net/coinbase-ceo-brian-armstrong-announces-switch-to-bitcoin-classic/