Seems to me that there is an ambiguity in the WSJ story that is being interpreted solely in one direction by news outlets.
"Both new models are expected to feature metal casings similar to what is used on the current iPhone 5S, with Apple expected to scrap the plastic exterior used in the iPhone 5C, these people said."
"Apple's plan to scrap the plastic casing for its new models comes amid reports from suppliers that the company is scaling back orders for the 5C because of weaker-than-expected demand. The 5C, which was released in September, carries much of the same hardware specifications as its predecessor, the iPhone 5, but with colorful plastic cases."
These quotations mean two possible things re: 5C.
1) They are scrapping all phones with plastic, including the 5C.
2) They are scrapping plastic for new models (but might retain the 5C line).
Seems to me the second quotation makes clear that #2 is the more likely meaning--the bigger phones will be metal, not plastic, but the "people" have nothing to say re: what happens with the 5C. I suspect it remains with a price cut and this was the intention from its initial release (as was readying bigger phones for Apple's entry into China, which prefers bigger phones).
Note also that the "people" referred to WSJ did not say this was a certainty to happen. Original story is, as usual, more nuanced than how it is being reported.