Many people here are missing the larger picture
Many are thinking about the past, the current day, and maybe a couple of years into future. Apple is planning much, much further than that. They have at least the next couple years worth of iPhones in some type of prototype form. They are throwing around designs for iPhones 3 or 4 years out, and they certainly have ideas and dreams for iPhone models beyond that.
Somewhere in that future there is an iPhone that is just a perfectly smooth iconic slab with a screen on front and a logo on back. No ports, no home button, no switches, no holes. The home button will be under the screen. Charging will be wireless and will work without sitting on a mat. Headphones are going wireless now. Syncing has already been wireless for some time.
They simply cannot do all that at once--look at the uproar over the headphone jack. There would be similar uproar over the ringer switch, volume buttons, etc., especially the Lightning port--people will absolutely rail against removing that. But make those changes over time? We will adapt and adjust. Another reason Apple can't do all this at once is simply that the technology isn't there yet.
So to get to that iconic vision without cataclysmic disruption to the users, Apple will remove one thing at a time, slowly over the years. Last year was the headphone jack. This year or next will be the home button. Some time after that, the other switches and buttons. Then the Lightning port. And eventually, if they can figure it out, the mic and speaker holes too.
Removing the headphone jack is part of that vision. People who claim the move is so Apple can make money on dongles and Airpods have no imagination or foresight.