Not really though. Explanations normally need a reason unless your some sort of populist politician ?
So, in light of one let’s go into depth. Face ID is ridiculously convenient because it works like magic and doesn’t require any user interaction with their device beyond gazing at the screen which is something they will do anyway. It removes all barriers to biometric security. It remains more secure despite scare stories about family members facial features or 3D printed masks fooling the sensor. What it does however do is take up a lot of precious space.
The sensor consists of an IR dot projector, an IR camera, the earpiece and a normal front facing camera. Miniaturising all that technology further is very difficult. The technology was derived from the original Xbox 360 Kinect peripheral. Apple brought the company behind it, Primesense in 2013. The Kinect was launched in 2010 and the iPhone X in 2017 so we can assume that behind the scenes research into making that all a lot smaller took place over a 6-7 year period. Going by further time scales it might take another such period of time to make it smaller again, leading to a 2024 release if at all possible.
If Apple’s design machine wants a notch cutout for a less intrusive front camera system then it may be that Face ID gets dropped entirely, despite being the better technology. It might be however that Apple keeps the notch and the rumours are wrong. In an era of indentikit phones that have to use their rear as a promotional tool to stand out, the notch provides Apple with a unique brand identity as recognisable as the iPod click wheel as a silhouette. Never underestimate the subtleties of instantly recognisable branding.
Touch ID isn’t the best biometric solution, being fooled by something as unassuming as
Play Doh in the past. It is still very convenient though, particularly via the classic home button. There are users who do not like navigation gestures as they are not an obvious ux feature and require some learning, however small. The reason Apple put the home button on the OG iPhone was to act as a safety net or sorts. It didn’t matter where a customer was in the OS or which menu they were buried in, one press and they were back at their home screen. The majority of users are not tech enthusiasts, something the press and the community often forgets. The best design is invisible design (like Face ID) but sometimes it is helpful to have a barrier of entry to the user is aware they have initiated an action. Face ID works whether you want it to or not whereas Touch ID requires the user to physically interact with something, a feature that prohibits anxiety.
Sony’s Xperia phones have a fingerprint scanner in the power button on the side of the phone. Sony are a company famed for their rigorous industrial design and their phones are no exception. This is a company that still advertises its phone cameras in terms of XXmm equivalent like professional models rather than vague terms like ‘ultra wide’ (How wide exactly?) and builds full manual controls into its camera app, something Apple doesn’t even do on its allegedly ‘professional’ line of devices. Their build quality is every bit as good as Apple.
As nobody uses home buttons anymore on Android devices they have 3 types of fingerprint scanner: in-display, side and rear. In display scanners use ultrasound to detect fingerprints and are quite convenient but easily broken by screen scratches, dirt and moisture. Rear scanners use an index finger to log in but put one in the wrong place, such as the higher sensor on the Galaxy S8 and it becomes impossible to reach without having to move your phone grip, risking a drop.
Power button sensors are placed where your right thumb (or left index finger) would normally sit when holding your phone. They require no grip change to use and therefore lower the risk of dropping. Every user knows where the power button is on their device and so unlocking is done in the exact process of turning the screen on, removing that UX barrier for the user. It is therefore actually more convenient than having a separate fingerprint sensor to the power button as unlocking the device requires only one finger motion, not 2. The case for Face ID being superior to Touch ID is that it requires no steps to unlocking the phone, remember so removal of any barriers to the user is better design. (Unless you are the of the home button minority) The
plethora of cases available for Sony phones would suggest that it is not a design problem for case manufacturers either.
To summarise Face ID is indeed the best current technology for biometric security but it does take up a lot of space. Of all the technologies available for fingerprint unlocking, housing the scanner in the power button is the most seamless as you would likely be pressing it to turn the phone on anyway. Apple already figured this out with the iPad Mini and Air lines so this would suggest they are warm to the idea. If Apple want more screen real estate via a notch then a power button fingerprint sensor is the only logical replacement for Face ID (which is still better!)