[fancifalmanima]

I don't think there's anything that would preclude the us government from selling bitcoin treasury bonds (accepting bitcoin with the promise to pay more back at a later date, basically). Even if the block chain didn't support it, the contract (bond) can still exist off-chain.

If it took off, and non technical people became more engaged in the space, I really don't see a reason to assume that traditional banks wouldn't accept bitcoin deposits and offer off-chain loans (re-creating the fractional reserve system we have today as well). Unless there was some law preventing it.