I'm fully on board with Apple's vision of a "wireless future," as my tech arch nemesis is the cable. At the same time, I own a pair of wired headphones as a backup to my Bluetooth headphones, and there have been several instances when the headphone jack in my iPhone 6S Plus has come in handy.
Sure, I could still use wired headphones with the iPhone 7, iPhone 8, and iPhone X, but only if I have a dongle or if my wired headphones have a Lightning connector, neither of which is as convenient as the good old headphone jack.
I'm a little worried that I'll have to adjust to using a dongle, which I'll surely lose, when I buy my next iPhone — if it's an iPhone.