According to Coinbase website, if the Hard Fork happens, Coinbase WILL NOT be keeping anything for themselves. They just won't be supporting the new currency. They are only supporting the proposed software fix or Soft Fork. The last I read is that there was over 80% backing the soft fork. If this goes through, this will be a non-event. Kind of like the Y2K event.....
I still may sell a major part of my bitcoin today. Just haven't decided to risk it or not.