The reason for the material switch, according to Kuo, is to differentiate the iPhone from rival phones that use aluminum and to boost stagnant sales.

Apple didn't immediately respond to a request for comment. KGI didn't respond to a request for a copy of Kuo's report. In the past, KGI has said regulations prevent it from distributing its research in the US.

iPhone sales growth has flattened, in part because customers resisted upgrading after last year's 6S and 6S Plus failed to include enough new features. Equipping future phones with more must-haves will help Apple put some pep in sales and compete with Samsung, as well as other phone makers.

Glass would certainly add to the premium look and feel Apple has historically given its products. It also offers advantages for wireless charging and antenna reception, according to Forbes.

Of course, glass has one major - and obvious -- disadvantage. It's more fragile than aluminum.

Apple used glass on the back of iPhone 4 and 4S, which led to incidents of shattered backs.

The glass expected to be used in next year's iPhone will be tougher and more durable than the glass used in the past, Kuo said, according to AppleInsider. So the new phone's casing would stand a better chance surviving a drop.

Glass is also heavier than aluminum. But that won't be a problem, according to the analyst, because Apple will switch from traditional LED displays to AMOLED screens, which are thinner and lighter.

One drawback taken of Kuo's forecast is that the glass casing and AMOLED screen won't show up until 2017, rather than in Apple's expected iPhone refresh later this year. Reports so far of the coming iPhone indicate few possible enhancements from the current model beyond stereo speakers and a dual-camera for the larger model. Such a scenario could disappoint consumers and investors alike.

Of course, all of this remains in the rumor stage. That said, Kuo has a good track record at nailing Apple developments.