With a 15.5-inch display and chassis, this isn't going to be an "Air" no matter what Apple ends up calling it. It will be well over 3 lbs and a big slab of aluminum. This is a MacBook Plus, not MacBook Air, simply because of physics.
There should be a rule that people who aren't physicists or physical chemists shouldn't be allowed to invoke "physics" to insist their view is correct. There's nothing wrong with anyone—physicist or not— making specific physical arguments. Indeed, that is encouraged. But if you were actually trained as a physicst, you would realize that general physical principles say nothing about whether either of us is right or wrong in this (which you seem to think they do). This is an argument about engineering details, not physical principles. We're not arguing about perpetual motion machines here.
We know 13.6-inch Air can fit an M2 logic board, so a 15.5-inch will have plenty of space. Without adding a fan, what would Apple do with the extra space adjacent to the logic board? Insert a plastic space filler?
It's not about the lateral space for the logic board. It's about the thermals and the battery. If you confine the processor to an M2, you can make the case thinner and lighter than if that same case design had to be thick enough to accommodate the thermals, larger battery, and fan that would be needed for an M2 Pro. Indeed, given the additional lateral space, they could make it even thinner than the 13" Air and still have good thermals and enough volume for the battery. [If Apple did offer a 15" Air in both M2 and M2 Pro versions, they're not going to have a separate case design for each.]
Indeed, with a 15" M2 Air, they could even bring back the front taper that made the previous Air comfortable to use, while keeping the max thickness equal to or smaller than the 13" M2's.* They couldn't do this with a 15" M2 Pro Air. [*I don't think they actually will bring back the taper, since Apple probably wants to maintain consistent design with the new Airs. But it would be cool to have a 15" with that design.]
Nope, the whole point of a 15" Air is to separate screen size and peformance,
It almost defies common sense to not offer M2 Pro, in my opinion....Consumers expect a larger notebook to have more power and an M2 Pro option makes sense.
i.e., to accommodate those customers who only need Air-level performance but want a large screen, and thus don't want to pay for, or lug around, a 14"/16" M2 Pro/Max MBP.
Yes, a 15" M2 Pro Air could be thinner and lighter than the average of a 14" & 16" MBP, because it doesn't need to acommodate the Max processor. But by allowing for a Pro option, Apple gives up the opportunity to make the Air thinner still and, to me, that defies common sense (given the target market of the Air).
Again, I'm not claiming I know what Apple will do, but my analysis isn't about that. It's about what I think it would make sense for Apple to do.