Any possible impacts I haven't mentioned?
Regardless of the other pros and cons of dropping the jack, the biggest downside could be that the iPhone 7 hype is currently shaping up to be:
"Here is the new iPhone 7, Apple's flagship product for 2016/17 featuring 100% less headphone jack!!! ...and, well, some minor technical upgrades but nothing that's gonna push the headphone jack off the headlines."
Samsung must be quaking in their boots.
If the iPhone 7 turns out to be bath/swimming pool-proof or features inductive charging then that would offset the loss of the jack. Currently, its sounding pretty dull. If the MacRumor roundups are to be believed, all the big changes are being saved for iPhone 8 - which would surely be a better time to drop the jack.
Oh - and PS: the floppy disc didn't disappear overnight with the iMac: it was
phased out of Mac PowerBooks before the return of Jobs - in the G3s the floppy became an optional extra (with the
advantage that you could use the slot for an extra battery, Zip drive etc.) before vanishing. By the time the iMac came along, the floppy was getting too small to be of much use - PCs clung to it because you needed a floppy to boot DOS. Of course, the iMac brought along a completely new form-factor, design language and USB+Firewire to distract from the lack of a flopppy.
First attempt to drop Firewire from the MacBook was a flop. FireWire, Ethernet, optical drive etc. were only 'properly' dropped when the rMBPs came out, also offering retina displays, SSDs as standard and a
significant thickness/weight drop. Oh, and (a) the idea had been 'trialled' with the MacBook Air first and (b) Apple kept the 'classic' MacBook (with optical drive, Ethernet, Firewire) for
ages afterwards.
So, yeah, the real problem with dropping the jack would be doing it
overnight without simultaneously offering some compelling new features.