Would something similar to libertyreserve work for USD fiat where there are exchanges in between you that would exchange USD for a the libertyreserve currency that was pegged to the US dollar. Only difference would be to make it a crypto coin that is pegged to USD. The exchange then would issue 1 dollar in the crypto coin and sell it with a small fee. They would make money from the fees and the coins sold would be able to reclaim there cyrptocoins for the original dollar they paid. Of course you would need to pay $1.02 or something to get $1 of this crypto currency.

The advantage is there is no exchange to hack, the USD cryptocurrency is backed by real dollars that are stored safely in a bank account, the dollars have fdic insurance, since the funds are in a bank account they aren't easy to steal, since its a USD cryptocurrency it is transparent and clear how many coins are issued and if the company is solvent.