It simply isn't reasonable to ask people to take the risk that their money can disappear because of an unbacked-up file.
exactly what i think. my "dream" is some kind of banking or credit card, that has an intrinsic unique key and a passphrase -- just like EC cards today have. your actual wallet is stored at a central bank and thats where the real transaction happens.
the device where you put the card in just get's a token for verification and that also enables instant payouts. especially, the "bank", where your wallet actually is, pays for you and also manages your wallet to get the confirmations later.
even better: replace "card" with "smartphone"