Will Apple keep the 5c design?

Every design of the iPhone survives for two generations (3G -> 3GS, 4 -> 4S, 5 -> 5S). But now we have a disruption, the 5c. What will happen next year? iPhone 5sc? Or is this just a one off and we will see a new redesign on the iPhone 6 and the 5s will remain the same design?