Having been ahead of the game with the launch of TouchID on the iPhone 5S, Apple has been somewhat guilty of resting on its laurels. Others have caught and surpassed the fingerprint sensor on the iPhone and biometric authentication is available on just one Mac - the MBP with TouchBar.
In contrast Microsoft and its partners have been making all sorts of leaps ahead with biometric authentication. Windows laptops support fingerprint and facial recognition technology, Windows Mobiles use retinal scanning for authentication and Samsung and HP have both released devices with both fingerprint and retinal scanners.
The recent legal judgements that a defendant can be compelled to give up their fingerprint in order to unlock a device has raised the profile of the risks inherent in the technology. It may be more convenient and more likely to be used than a pass code, but the possibility of being forced to unlock a device (by law enforcement officers or worse) does reduce the inherent security of the solution.
Apple has clearly recognised this and rumours that the next iPhone will support facial recognition have been around for several weeks now. Evidence that these rumours are on the mark comes with the news that Apple has bought an Israeli startup specialising in facial recognition.
RealFace is a couple of years old and has been used in at least one existing iPhone app. It seems likely to me that Apple's purchase hasn't just happened and the two have been working together to develop and integrate the technology into the next major release of iOS.
It's unlikely that Apple will switch from fingerprint recognition to facial recognition unless it can achieve the same levels of accuracy - making the user experience worse isn't likely to be something that Apple would countenance.
However, given the age of RealFace, its success with iPhone apps and Apple's desire to catch-up in the authentication space I'd suggest that this will appear not only on the new iPhone, but new iPads and Macs in future too.