Commercial Banks, on the other hand, could use some sort of digital gold - a cryptocurrency they manage / own and can transfer value between themselves very easy. This could be something we may see in a near future. Such approach makes more sense.
It's more or less already happening. Ripple has various products that they managed to install in various banks across the globe, which should make transfer of value much easier and faster, so that's technically the first step.
I'm however not sure how long banks will be using Ripple's services, but it's definitely a start of something that might stimulate them to create their own system that works better and doesn't require them to pay an external party such as Ripple.
Banks are thriving on controlling every aspect of their operations, so it only makes sense to drop Ripple's services at a later stage.