> ...continue to be stuck using this very old connector
The question is: what's really wrong with the old connector (from a consumer's PoV)?
When they abandoned ADB, SCSI etc for USB (and at least it was clear that the new thing would end up being better, soon. Abandoning VGA could have been similar except it meant a shift to a parade of different things (DVI D/A/both; DP, mini-DP, etc) which only, (mostly) converged when the rest of the industry finally caught up by standardizing itself on HDMI. And the consumer lost as well as won in that. Switching the MacBook to USB Type C was a transition similar to the first USB one: eventually it will be great but the infrastructure hasn't build out yet (believe me: I own a MB, love it, but don't have any peripherals).
But the TRS connector wasn't preventing much of anything.
I think the real significance is that they are going to a port-free device with inductive charging like the watch. But they can't do that until enough people have switched over to wireless headsets.