Anyway, this is not really a problem, because modern banks all use electronic currencies already, and if their computer systems failed, people would lose money the same way as they would lose bitcoins...
I haven't heard any incidents that depositors lost all their money because their bank's computer failed... and there's always a FDIC to fall back on.
The more I think about this, the more scenarios I can think of:
1. File or machine corruptions
(once you make an transaction, the previously backup wallet file become useless, correct?)
2. Some % of new users will abandon their bitcoin wallets or bank accounts, along with whatever balance in them.
3. If there's an error in the address, payment is sent to a "no man's land", the BTCs are essentially lost forever.
My ballpark estimate is there will be 5%~10% bitcoins disappear from circulation every year and this will create significant deflation pressure, once the generation curve flattens.
