In a decade, the headphone jack will be all but extinct.
Why? Several reasons.
First, money. 3.5mm headphone jacks aren't free. If I take a look over on DigiKey, I can buy them for about 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.
Then there are the upcoming changes to the USB Type-C standard that will make it easier - and cheaper - for companies to use the USB-C port as the headphones port. Not only does this eliminate the headphone jack itself, but also the analog to digital circuitry that it requires. This means fewer components, and that in turn means a cheaper bill or materials and possibly a thinner device (because we all want thinner devices, right?).
There's also the fact that the headphone jack is 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 is possible to make a headphone jack water- and dust-resistant, it costs money, and it's still a potential failure point.
But, finally, we come to the biggest reason of all why the headphone jack is on the way out: put simply, 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.
This is how in less than a decade we've come to a position where almost all smartphones look like 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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