Doesn't that make sense? You ought to have seen the number of headsets that ended up destined for landfills at the end of our flights until we began charging for them on most routes. The idea when the disposable headset was introduced was that people would keep them to re-use on future flights. Few people did, so most headsets ended up in the trash bag. The $3 charge has definitely encouraged people to keep them, and waste has been drastically reduced.

Oddly enough, the few complaints about headsets no longer being free that I have heard on board have mostly come from people who had umpteen opportunities to keep the old, free ones, but didn't.

As far as I know, the adapters will remain free until they're no longer needed, i.e. when the Embraer and A-330 systems have been converted to single-prong jacks.