I was kinda holding out for FaceID on my MacBook Pro when I bought the 2018 model (I had a 2011 model beforehand) but really touch ID is fine, most of the time it unlocks based on my Apple Watch anyway. Also when I go to use my MacBook my hands are already on the keyboard area. Still FaceID would be better.
It makes sense to put it in the iMac as Apple often likes to flex with that one. I think it's unlikely though that any AppleSi computer will not have FaceID aside from MAYBE the Mac mini. (Even then, I see them either unveiling a new external monitor designed for consumers to pair with the mini and Macbooks that has FaceID) Even with the mini though they could position a FaceID projector on the front and just tell you that if you want to use Face ID you should position your Mac mini so that it can see you.
I think it's unlikely that the iMac is the only AppleSi Mac they'd unveil. They're almost certain to have a version of the 13 inch MacBook Pro (probably the whole laptop line up) as laptops made up 80% of Apple's sales all the way back in 2017.
Also for those who think the FaceID projector is thick, it really isn't. Look at a teardown picture. Also Apple doesn't have to place it beside the webcam. They could easily redesign the hinge/vent area on the MacBook Pro and position the dot projector down there. It just needs to scan a distinct part of your face, your double chin and nostrils would probably be fine for the scan.

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I wish Apple would unify its product line instead of breadcrumbing its client base over the course of 5 years. I'm glad they seem to be favoring stability over rushing out with glitter and yoyos, but how many times do people need to sit through the same "wow?"-factor of a re-introduction of technologies that have existed in production for 5 years?
I appreciate your frustration to their iterative approach. For example the iPhone 12 is going to have design language that's been on every version of the MacBook Pro since they went unibody, and has been on the iPad Pro since 2018, and still isn't on the Apple Watch. (Oh can you imagine how crazy people are gonna go when a boxy Apple Watch is released?)
On the other hand, Apple sometimes backs away from design ideas that aren't popular. Aren't you glad their whole laptop line didn't go Butterfly right away? Aren't you glad that every product didn't go portless when the watch did?