Did anyone think at this? How would a bank work? How could you loan bitcoins and get interest for them in an economy with just 21 milion BTC limit?
There will be no area of verification for the bank loan of bitcoin, unless you give your wallet to them and the password to guarantee that you will lay. Likewise, bitcoins price is unstable, so how can they measure the interest rate for that.
Well, the fact that this coin is deflationary does not necessarily mean that you cannot get interest from it. However I would admit that the interest rate would need to be too high and not competitive with crappy fiat currencies.