Every once in a while, market watchers start a rumor that plastic will replace metal in device chassis manufacture.
Even if I had been keeping track, I'd probably have lost count by now.
Anyway, some parties are concerned that Apple's reported decision to adopt plastic chassis for its next-generation iPhone will cause a current that will affect the rest of the industry.
To be fair, there would be some motive, as aluminum and other metals are more expensive, albeit more durable too.
On the other hand, while plastic is cheap and light, it probably won't take over too much of the mid-range smartphone and tablet segments, and probably no share of the high-end one.
Thus, major suppliers are confident that metal cases will stay in strong demand for a good while yet.