iPhone X

The plan is to remove that next year and sell it as iPhone X1. You want to this milk this for profit every year.

Did they botch the Mac Air upgrade similar to the Pro now? Or is it still usable?

This is my only gripe with Apple. It's an incredible PITA to share devices even temporarily. You have to log the primary user out of their phone, login with your credentials and we are in business. This whole process is so long and frustrating that it forbids any sharing experience. I do wish Apple or someone made sharing devices a lot easier.

The scenario you describe sounds impractical, unlikely and unworkable, a very edge case "iOS fan family".

Walking out the door with just "any device" that is laying about? Nobody wants that. For one thing, an object like a phone is a personal device, not a sugar bowl passed around and left anywhere.

Your son and daughter will want their own devices, and it makes sense to give them their own devices such as your old phone or cheap phone. For one thing, when you hand your kid your phone you no longer have a phone. Someone might text or call, or the kid will burn through your battery with some game.

This only scratches the surface of what's wrong with your idea.

Couple of issues here, speaking as a facial recognition developer, of arguably one of the leaders in the industry.

1) The use of 3D data is a step in the right direction, but to use it reliably it has to constantly re-calibrate to the individual(s) it is supposed to pass. This is very important and a constant issue if using a person's 3D depth data as their face for authentication. My employer pioneered the use of 3D data for facial recognition, via 3D reconstruction, before scanning and depth cameras were feasible. In doing so, we became aware of the significant variation an individual's 3D facial form undergoes during any time period: different times of the day, yes, significant 3D facial form transformation; different days, definitely. Females significantly more, as they experience 3D form transformations simply from their menstrual cycle. Men who drink, less so than women, also gain significant facial form transformations on a weekly basis. Over the course of a season, everyone undergoes significant 3D form transitions, to the degree authentication is not reliable unless constant re-calibration occurs. Which introduces issues of system failure after indeterminate lapses of use, or sudden physical transformation - such as an accident, where your face is swollen. A person could be attacked, and their face altered to the degree their phone no longer authenticates. A person could fast for 2 days, not use their phone, and it will no longer pass.

2) They should be using multiple biometrics for authentication. The facial image in combination with the depth information, if treated separately with completely separate verification trained algorithms, only counts as two biometrics. Reliable authentication of a device attached to one's credit cards and finances requires a MINIMUM of 3 biometrics. They could solve that with the addition of Touch-ID or the addition of a pass code in addition to the face image and the face 3D depth data. But that borders on 'inconvenience', and I feel consumer pleasing stupidity. Sometimes being safe should require an extra step, simply so the consumer has the assurance their data is safe. It's like hearing the click as the lock on your door seals. Too automatic, and it's insecure because one never knows if it is active.

However, ignoring the face as authentication, the iPhone just became a very slick 3D avatar creator.