Ask HN: How can Coinbase make good on deposits/withdrawals?

If 10 people have 10 bitcoins that they bought from coinbase for $10, and now the ‘market’ says 1 BTC = $10,000, and all 10 people want to cash out, how does coinbase make disbursal? Obviously there are new people coming in and buying BTC at a higher price, but due to the surge, can Coinbase really honor all deposits?