I think the 15 inch Air 'concept' was to address the perceived issue that Apple demanded £2.5k for a large screen laptop, so there might have been a market for a £1.4k large screen laptop.
I think that makes sense on paper, but in practice I suspect the 15 inch Air is not really competing with the 16 inch Pro, but rather the 14 inch Pro and 13 inch M2 Air, the former (particularly M1 Pro models) being quite a lot better for not much more money once the RAM/SSD specs are equalised and the latter being a bit cheaper and more portable.
So the 15 inch Air has a market, but not a very big one.