Even then it is a horrible idea to remove the headphone jack. Many people have amazing (and expensive) headphones, why would they want to switch. An adapter is always a hassle which makes the phone even longer in the pocket.
Apple is getting to bold and didn't think this through. Steve Jobs wouldn't have approved. The iPhone is going to have be very amazing to make me buy it without a headphone jack. A built in holographic projector might convince me.