Not sure about that. The 5c is basically a 5 that's built slightly more cheaply, so that it fits in at the bottom of the price spectrum at all points. The 6 currently is two notches up from the bottom, and because of that it may be that Apple decided that they didn't want to dilute the 6's brand with a cheapo version.
Another year down the line when there's an iPhone 6S and the 5C has been dropped, that's when I'd start expecting something like a 6C, though perhaps it would just be a 5SC. Not necessarily those names, exactly, but something following the pattern of "Drop the bottom-end phone, replace the 2nd-from-bottom with a plastic version."
Another year down the line when there's an iPhone 6S and the 5C has been dropped, that's when I'd start expecting something like a 6C, though perhaps it would just be a 5SC. Not necessarily those names, exactly, but something following the pattern of "Drop the bottom-end phone, replace the 2nd-from-bottom with a plastic version."