For some reason, I'm not that worried. I would be worried if this was concerning normal users but not in this case. With the Blackrock, and SEC involved into all of this. I can't imagine them even trying to pull such a move.
Regardless though, one should not store his funds for a long period of time in any exchange.
It sounds like a non-event to me. Big enterprises require many kinds of special stuff from their providers all the time, so it doesn't really make sense to me that someone would pull all their BTC from Coinbase simply because someone thinks that they are depositing paper money.
That being said, I do not support Coinbase at all.