There are already a lot more USB-C equipped devices than there are Lightning equipped devices, and the gap will only increase.
I don't disagree, but this doesn't address the fact that there will be for many years to come many devices people may want to plug their headphones into that don't have USB-C, or Lightning. Not just computers and phones either. So unless people are only using their headphones with a couple of brand new devices, then they are going to need adapters. And if they are only using their headphones with a couple of brand new devices, then it really doesn't matter whether it's Lightning or USB-C.
I'm not sure why you'd prefer Lightning over USB-C: they're both small, reversible, and USB-C has the benefit of not only being non-proprietary but also more capable. I'd also argue that Apple's cable design is less durable than their competitors, which is a problem when they've got a monopoly on a proprietary standard.
I've never had a single Apple Lightning cable fail, though I acknowledge the competitor's cables seem to be more substantial. But I don't see the relevance, since most headphones will likely incorporate much higher quality Lightning cables, just as they currently do 3.5mm over what Apple offers. As for why I like Lightning over USB-C? For starters, Lightning is smaller. It's also a single connector that inserts like a flat 3.5mm plug. USB-C is a male/female combo, the plug inserting into a jack, but there's a tongue inside the jack, that inserts into the plug. Perhaps it's a prejudice that goes back to the Mac vs. PC days, when all PCs had male connectors on the motherboard, which if a pin broke or was damage, the whole mother board had to be repaired. Macs were the opposite, the peripheral cables had male pins, so if they broke or were damaged, only the cable had to be replaced. And then there's the ever changing USB connectors, I have on my desk right now 6 USB devices that all have a unique cable connector. I just don't see this kind of fragmentation changing in the future as different technologies develop. And then finally, there's potential compatibility issues between desktop USB-C peripherals and iOS compatible peripherals. In my mind, it's simpler to know you buy a Lightning accessory and it will work on the iPhone, rather than wonder if a particular USB-C device is compatible, or may cause damage. I'll never forget how confusing it was in the 90s with Iomega Zip Drives which had 2-pin parallel PC only drives, combo Parallel/SCSI drives, and 25-pin SCSI only drives.
It's likely the functionality of USB-C will evolve in the same manner as HDMI and USB 2.0, meaning the port will remain the same for years and be backwards compatible. Apple knows this - they're already utilizing USB-C on the latest Macbook.
Well one can hope. I just don't want to bet the farm on it just yet, in the form of investing into native USB-C headphones, which are still going to require an adapter to connect to legacy equipment. While you may be right, I don't think Apple's use of USB-C is the best example given their introduction of Firewire which failed to take off, and ultimately morphed into Firewire 800 which required adapters, and finally Thunderbolt which required more adapters. And in the end, Apple only included one port, which more or less emphasizes their push toward wireless. In my opinion it was too soon to force a computer user to make due with one port, because wireless data is not quite there yet for the kinds of huge media files consumers are used to working with these days. And in that respect it's a pretty good comparison to the transition form wired audio to wireless.
Yes, the 30-pin connector was ubiquitous for Apple devices, but discounting accessories it was never a port that was included anything other than Apple made (iOS) devices. If you'd rather not have to replace all of your Lightning cables I think you can understand people feeling the same way regarding the 3.5mm jack?
I absolutely understand. But If I have to accept that the 3.5mm jack is going away, I'd really rather not replace all of my Lightning accessories just yet for USB-C either. Apple may in fact lose this battle and eventually accept USB-C on all of their devices, but by that time, I will have gotten the use out of my Lightning accessories, and the future of the USB-C connector will be a little more clear.
Fair enough - but again a similar argument can be applied to the Lightning connector, which isn't as capable as USB-C.
I'm not sure how capable Lightning is. It has 17 connectors now with the iPad Pro, and that provides for a lot of bandwidth for a mobile device. USB-C only has 7 more connectors, and I'm not sure there's anything that utilizes all of those pins yet either, especially when 4 of them are dedicated to USB 2.0. Since Apple's Lightning connector allows for dynamic pin configuration, and smart cables and connectors, it may well be a much more capable interface once Apple opens it up further, at least for mobile devices.
Something I've just thought of - are the internal speakers powered by the same DAC/Amp that the 3.5mm jack is? If so removing the 3.5mm jack will have even less impact in terms of increasing physical space inside the chassis as the DAC/Amp will remain in order to drive the speakers. Also, the phone will potentially be powering two DACs/Amps if there's also a wired external one for the headphones?
Yes, I believe there is only one internal DAC and amp which serves all analogue audio needs. However, as far as I know the iPhone does not power the DAC while audio is being streamed over wireless, or Lightning for that matter. It just wouldn't make any sense. That's why the user selects the audio source from a menu, and typically the headphone jack and BT connected device cannot output sound at the same time. So there's no powering two DACs at the same time. Further, if Apple only needs a DAC to power its single, low-quality, mono speaker and earpiece in the iPhone, the DAC and amp can be smaller, much lower quality themselves, and also cheaper to manufacture. Regardless, even now the current DAC and amp take up significantly smaller volume than the 3.5mm jack alone, which measures some 4x4x15mm or 240 cubic mm.
I think you frame the pro argument well here and it's definitely something I hadn't considered - the end goal ultimately being wireless. Thinking of it this way definitely makes me less cynical about the (rumoured) decision.
Well, I have to admit where Apple is concerned, I'm always somewhat cynical. It's not like Apple is some wholly altruistic company. If Apple does this, they are doing it primarily for themselves, even if ultimately the results may better serve the customer. However, I don't believe hey aren't doing it solely to screw their own customers, despite a few are definitely going to feel that way, as I myself have many times in the past. Currently, I feel that way about the fact I have to use an Ethernet adapter on a "Pro" MacBook in a business setting. But, I'm so used to using adapters over the years, I've just come to accept it as a part of life now ... which is probably why I don't see headphone adapters as much of a big deal -- I lived through the 70s & 80s when I needed adapters to use my 1/4" headphones with new 1/8" Walkmans, and then the 80s and 90s when I needed adapters to use my 1/8" headphones with 1/4" equipment, and then the 90s and 2000s when I needed adapters to use my 1/8" headphones with 2.5mm headphones, and then again to use my 2.5mm headsets with 3.5mm phones.