What ripple promises is the transactions and how cheap they are, they are not promising this to banks directly, of course it is worked best when its b2b and banks work with them but they are suggesting it in general so anyone can use it. If you need to send money to someone using ripple is a cheaper way than using a bank or something like western union.

However, considering they are using their coin to supplement their system and make sure they keep on selling the coin when they need funding and buy it back when they have funding to keep it alive is just shows everyone how centralized the coin itself is. It is probably the most manipulated coin out there and it sits on second or third place almost all the time when it deserves more like 30th spot at best. Can they switch from purely bank to "best transaction method worldwide" company ? Yes, but it won't change anything for the coin, just for the company.