UPDATE 23/01/2017: Analyst Ming-Chi Kuo has new predictions for Apple's Touch ID: he says that it might be refined or perhaps replaced altogether.
Apple is said to be working on new biometric technologies that would make bezel-less designs easier to implement. What will happen is that Apple will replace its current capacitive technology with an optical-type sensor.
As it is still in development stages, it is highly unlikely to debut on this year's iPhone 8. Other rumours are that Apple would incorporate the Home button's functions right into the screen as opposed to the current separate, physical button.
Full-face recognition might also be on the cards, instead of simply relying on fingerprint or iris recognition but this is also something being worked on and unlikely to appear very soon.
What Apple is doing is using a new stainless steel forging process for its chassis frame. It'll be a departure from its usual CNC machining, part of an overall new design.
No more aluminium back - instead there will be two reinforced glass panes with a metal frame in the middle. That metal bezel will be specially made with the new forging process, that promises enhanced sturdiness as well as reduce manufacturing time and costs.
Why a new process? It seems that it will be 30-50 per cent cheaper than the current unibody CNC machine process, and yet offer more stable quality control. This will likely help prevent cases such as the Bendgate issue with the iPhone 6.
As many iPhone users had held off getting the iPhone 7, anticipating the release of this year's iPhone, there's a lot of pressure on the company to get this phone right and properly set itself apart from the Android competition.