Banks do have a role

1. We still take the risk on the transaction, and do put our balance sheet at risk in it, just in an indirect way
   
2. another banks was required to provide the funds, just on different terms
   
3. the place to put the longer chain of funding/guarantees/risk still needs to be a bank, for it to be credible - you need to have "skin in the game"

In fact, one of the reasons why I dont think Chris Cook's model will work is that it has been proven by reality not to work: Mortgage-Backed Securities, repackaged and resliced and resold to other investors, with the initial dealers not taking any of the risk is exactly what his model is about.  And the result is what you would expect when the people that cook up the paper and those that hold it are so separated.

You need banks to assess risk - and to put their good name on the risk by holding it themselves.

In the long run, we're all dead. John Maynard Keynes