[nikcub]

There's nothing about blockchain's that prevents them from scaling beyond single digit transactions per second - you're referring to the design decision Bitcoin has made to opt for a smaller blockchain in order to ensure distribution and decentralization.

A settlement blockchain between financial organizations doesn't have the same design parameters, and could conceivably run larger blocks, shorter block times, or not store block history at all but rather reach consensus on state (which is what Ripple does)