What happens when Facebook becomes a Bank?

We know that Facebook is now number two on Alexa only one place behind Google. We know people spend 7 hours a month on average using it almost 4 times more than Google. Based on its continuing growing it should catch and pass Google in 2011 and could reach a billion users say by the end of 2012. One billion users. That's alot. By then it should be a public company armed with $10bn of new working capital.When you have an audience of that size you can sell them lots of things. You can help them buy better. In fact you can sell them everything negating the need for many existing and costly suppliers and their overheads. Many. Obviously you can offer them discounts through group buying. Cellphones, laptops, cars, flights, holidays, gas, electricity, groceries to name but a few. But then when you think about it you want to manage all your members transactions. All. Everything they buy and everything they sell. And at the end of the year wouldn't it be nice if you could complete your members tax return negating the need for most of the Inland Revenue and thousands of civil servants. And then how about manage your members patient records so you can get the best deals on pharma products and healthcare too.So what happens to the existing banks when Facebook becomes a Bank?It starts with a Facebook piggy bank, payment system and credit card. Then it's a savings account and a loan perhaps for university. What about a mortgage, life insurance, health insurance, car insurance, house insurance and a pension? Afterall with a billion users these should be the best deals on the planet. Volume speaks price. Low price. This is before you offer your members peer to peer lending like Zopa giving them better interest and lower risk on their savings.Could it really happen? Are the existing banks holding your attention right now? Do you trust your existing bank? Do you trust Facebook to manage your money? Would you lend Facebook money? Would you invest in Facebook's public offering of shares?I guess trust is the killer app and it all depends if Facebook can pull that off. My three kids already run their life on Facebook. Is it a big leap to run their money there too? With a billion users and 10% choosing to bank with Facebook that's 100m customers. Wouldn't that make Facebook one of the biggest retail banks in the world? The Friendship Bank. That's a nice tagline.Should the existing banks be thinking about this? Afterall we know the governments are trying to make it law to separate retail banking from investment (these days called Casino) banking.What do you think?