The exchanges are not sophisticated at all. No single exchanges have opensourced their wallet technology. Kraken, Bitstamp and Bitfinex are using BitGo, a private source solution. The first would be to opensource a enterprise grade wallet which can be used for exchanges. And that's exactly what I'm working on. Then develop the procedures to secure funds with operational professionalism. Use of multi-sig is standard, but its not enough. Cold-wallet and transaction monitoring, deposit insurance, in combination with on-chain will develop over the next 1-2 years to keep deposits safe.