Could Supermarkets Take Banks?

Tesco recently announced that it will offer mortgages this year. It already offers many bank services including credit cards. Tesco banking sector grew at 15% this year. In France, Carrefour already offers a number of banking services and this sector is growing faster than the retail supermarket. The newspapers in Britain speculated that with the current poor opinion of banks by customers, John Lewis the well known large retailer could become a favored bank as it has such a good reputation for value for money. In the USA whether because of regulation or inclination, supermarkets such as Walmart only offer their own credit cards and have not moved into other financial services.
The question that is central to this is whether the supermarkets, with their huge customer loyalty and brand recognition can become significant players, and maybe displace or buy out banks? I worked for years at the Financial Times and they have a branding department. What they discovered was that the FT brand only extended so far, they could sell diaries but not luggage for example, customers were stretched to see the FT as a clothing maker, they saw them as anything to do with the City of London. Now I think that the supermarkets have a very broad brush brand appeal. After all they sell everything from Apples to TV's. I do not think that it is too much to suppose that they can beat the banks, certainly in terms of retail. It actually makes a lot of sense as one goes to the supermarket weekly and if the bank was right there, great!  Also one would expect supermarkets to lower costs, that is their tradition. Certainly they have in other areas, for example a Tesco phone albeit using leased Orange bandwidth is cheaper than all the other suppliers of phone connectivity.
In my opinion this is an opportunity waiting to happen, and first players will be rewarded.