Funny enough, that shouldn't be a challenge for Apple since the world's slimmest smartphone ever made actually has a headphone jack[1], so Apple excuse of not enough space inside the phone is horse shit to force everyone into the Airpods ecosystem.
What's the difference in this case? Volume is a multiplication of dimensions on all axis. If they didn't compromise on thickness that means they have more international volume available to reduce the other dimensions which they didn't as modern iPhones don't lack depth either, barring the mini, they're all quite large on all axis.
