I have a hard time seeing them keep around the 5s. The finishing is too high end to sell at the price. I think they'll update the 5c with 5s internal and still call it the 5c.
This is not going to happen. Then what's the entry level iphone? The iPhone 4s still? They definitely won't put the 5s internals in any phone and sale it for free.
The lineup most likely looks like this
iPhone 6
iPhone 5s
iPhone 5c
The lineup is different for one year and people thinks that they will do it every year. The iPhone 5s is STILL the top selling phone in the world. Why would they discontinue that? The 5 at this time last year was no longer the top selling phone.
My point being the 5s is staying the 5s. They can't put the internals in the 5c case and call it the 5c ... Then there's no entry level phone