I’m in my late 30’s, and I was a high school educator for about a decade. Teenagers have become quite comfortable holding an entire conversation while wearing earbuds. As an ancient and outdated old person, my initial gut reaction was that it was… a bit rude(?); however, these teenagers just internalized that audio pass-through was a thing, and wearing earbuds didn’t indicate a lack of attention to the conversant. My point being, we may not be comfortable having a conversation indoors with sunglasses on today - but that could change in a flash and only ‘old people’ would even notice.
The AirPods are really the first mass-market augmented reality device. It's so well done that no one even thinks about them that way. That's how it'll need to be with visual augmentation, but there's no reason I've seen that we won't get there eventually. I'm bullish on Apple being the first major player here in part because they already are, by a huge, huge margin, the biggest player in augmented reality.
Apple is IMO the only company that seems capable of simultaneously tackling the form factor, outside-viewer perception factor (AirPods are fully socialized, as you mention), inside-viewer perception factor (AirPods on transparency really do feel 99.9% fully "transparent")
There is a major difference between earbuds and sunglasses. There is a lot of subconscious communication that goes on with facial gestures (including but not limited to eye gestures). This is where the sterotype of poker players wearing sunglasses comes from.
Would the new generation be get used to it? Probably. But that does not mean it is healthy. We have gotten used to a lot of things that are objectively bad for us.
Yeah, it could be a “bad thing”, but it won’t be a bad thing just because prior norms have been broken.
We’re already deep into the process of merging modern technology into every aspect of our lives, and in some cases it’s been bad. In some cases it’s been a necessary evolution to survive in a modern society. In some cases, it’s been good.
On the one hand, I worry that face helmets will further erode human connection, and people will live in a lower resolution reality than what is possible with direct human contact. On the other hand, the current reality is that more and more people are looking down into a slab of glass instead of up/out at the world around them.
It could be that the ultimate version of AVP (some kind of glasses that are barely more noticeable than AirPods) is what gets people to look up/out again.
The “bad thing” is arguably already here, and it’s just a question of whether future tech will make it worse, or do a better job of merging the real world with the digital world, enabling people to participate in both instead of disappearing into their pocket computer.