This has always surprised my as someone who's owned a couple of pairs of B&W P-series headphones (P5 then PX). Portable headphones should be built to last, not just flimsy plastic. B&W got it right with metal construction (and with the newest PX models forged carbon fibre), no surprises Apple is building robust headphones too.
What B&W provide though, is a really solid benchmark (of many) (with the exception of spatial audio - which from Gruber sounds like it still has some shortcomings to overcome). They're £200 cheaper, really substantial and solid construction (with a proper hard carrying case - although similar limited folding), the newest carbon models will be noticeably lighter (if still a substantial 310g).
Obviously the Sony XM4s and Bose 700s are well in view too (although plastic construction can make them seem a less premium alternative).
I expect these will sell relatively well, but I can't see them flying off the shelves like their in-ear namesakes in such a crowded and competitive market, even with Apple's software bonuses.