In his latest note, analyst Ming-Chi Kuo of KGI Securities says that on the basis of Apple differentiating the Jet Black iPhone 7s by their capacity, the company may take a similar step for the 2017 iPhone.
He notes that it is not possible for Apple to use all-glass casing for the 2017 iPhone since a metal frame needs to be present in between to enforce rigidity. Instead, the company will likely use a stainless steel frame, which looks better than aluminium. However, since stainless steel costs more than aluminium, Apple will be using it only for the higher-end variants of the 2017 iPhones.
Apple already employs a similar strategy with the Apple Watch. The base variants of the smartwatch come with an aluminium body, while the higher end variants feature a stainless steel finish.
Kuo also believes that Apple will be using a glass front and back for the 4.7-inch and 5.5-inch 2017 iPhones. It was previously rumored that the company would only use the glass design on the bigger iPhone 7 Plus. He does note that the glossy metal casing and glass on the 2017 iPhones would be prone to scratches and would make using a case with the phone a necessity, just like it is with Jet Black iPhone 7s. To ensure that the glass does not crack easily, Apple will be using a 2.5D glass instead of the more commonly used 3D glass nowadays.
A new all-glass design would be reminiscent of the iPhone 4, which also featured glass panels at its front and rear. The handset was popular for its iconic design and antennagate that was regarded as among the worst tech fails of 2010.