I'm willing to bet that something else will replace it.
Audio isn't that tough a problem. Nyquist limit, etc., etc. Let's say we do 5x that for the audio purists - 100 kHz. That's slow - very slow. In-
air ear [sheesh] speakers don't need much power. Amplifiers are very good, so not much electrical power would be needed to send the signal from a phone to an in-car amplifier or whatever.
BlueTooth bandwidth keeps expanding. Wireless audio is going to keep improving. Yeah, batteries are a problem, but batteries are getting better (slowly).
[edit:] Also too,
wireless power transfer is a thing, but TANSTAAFL.
But even with the many benefits of wired connections, it's silly (IMHO) to believe that it's going to stay via 3.5 mm connections for the next 50-100 years. There are better ways to do it:
1) ways that don't take up so much space inside the phone.
2) ways that are more reliable (MagSafe - Apple's patents won't last forever, or could be licensed (but is a real problem))
3) ways that enable additional functionality (e.g. power and audio and video via one smaller connection - e.g. a MagSafe Thunderbolt X) for VR, audio, brain-wave monitoring and tweaking, insulin monitoring and delivery, bill payments, etc., etc.
I'll ask you the same thing I asked Drew - you still using your paper tape reader?
Remember when Ethernet used huge ~ DB-25 connectors and taps into ~ 1/2" diameter coax?
Sometimes it is indeed too expensive and too painful to change from existing standards. But 3.5 mm audio jacks aren't in that category, IMHO. Similar arguments were made against replacing micro-USB.
My $0.02.
Cheers,
Scott.
(Who expects BlueTooth will eventually get good enough that it won't matter (to all but the top 1% of audiophiles) if the 3.5 mm jack is gone, but that the 3.5 mm jack will also be supplanted by something better.)