A couple of years from now the 5C might be the new entry level 4. We'll see how Apple meant to do it. It'd make sense if the update cycle of the 5c isn't annual, instead pushing production costs down and keeping the design separate from the top line. The C and S might look somewhat similar today, but in a few years it'll probably be even more different from the top line, and cheaper, making it increasingly more appealing as an entry level phone.
Just my thoughts.