I see many comments about what's wrong with Coinbase. What would a secure bitcoin exchange look like? A few of the features have been thrown out, e.g., little o

I see many comments about what's wrong with Coinbase. What would a secure bitcoin exchange look like? A few of the features have been thrown out, e.g., little or no hot storage, two-factor authentication, (some) insured deposits, multisig-protection, decentralized services, etc.