"... if Apple drops it for the iPhone and the iPad, other companies won't be able to resist copying the move. Oh, sure, they might hold out at first, but eventually, they will all follow suit."
I made the move to Bluetooth headphones years ago so it never really bothered me that the headphone jack's days were numbered. And even when, many moons ago, I did use corded headphones, I hated the headphone jack for its unreliability. It's a mechanical device, and as such it's prone to damage and wear. Not only that, but it acts as a hole that dirt, dust, water, and random pocket schmoo can use to get into your device. While it's possible to make a headphone jack water- and dust-resistant, that costs extra money, and it's still a potential failure point.
Headphone jacks also aren't free. If I take a look over on DigiKey, they work out at around two for a dollar if I buy a thousand. Companies that make smartphones and tablets buy them in greater quantities, so they can get them cheaper than that, but I'd estimate that even at the cheapest end of the spectrum, they cost about $0.10 each.
And that's just the jack; it doesn't include assembly.
Any component you can do without means money saved, and when you're dealing with razor-thin profit margins, even a couple of cents saved per device adds up.
USB-C also makes it easier -- and cheaper -- for companies to dump the headphones port. Not only does this eliminate the headphone jack itself, but it does away with the analog-to-digital circuitry that it requires. This means fewer components, and that in turn means a cheaper bill or materials and a thinner device (because we all want thinner devices, right?).
But the real reason we've seen companies abandon the headphone jack is because Apple dropped it. Yes, they might poke fun or hold out for a while, but its days were numbered as soon as it was dropped from the iPhone.
Do we now mourn the passing of the floppy drive, the optical drive, or the 30-pin iPod connector? No. And the same will be true of the 3.5mm headphone jack.
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