The main advantage is that Apple can offer a native Lightning headphone jack for its customers. Apple is certainly not going to remove the 3.5mm jack on its iPhones, and require their Lightning headphone customers to use an adapter with their Macs.
Makes no sense to me.
Apple won't put a lightening port on the Mac, its crazy. 3.5mm Headphones are everywhere and higher quality. If people want wireless headphones, and I have 2 pairs for convenience at the gym, but not for quality, then bluetooth is fine. I do not believe a lightening or USB-C takes up less space than a 3.5mm socket.
The second advantage is charging. Anyone who is already using an iPhone and iPad already has multiple Lightning cables. This means if someone is traveling and forgets their USB-C charging cable, they can just use their iPhone cable -- moreover, they only have to carry their lightning cable. Also, for a power user, it allows them to charge their MacBook with a Lightning cable keeping all of their USB-C ports open for data. Additionally, it will most likely accommodate any Lightning adapters they already own, which instantly gives them ports for HDMI, USB A, and SD cards, without having to buy new USB-C adapters. All of this will be huge for customers buying new USB-C only MacBooks.
I will concede there is a slight truth to that, but if apple are to be all usb-c moving forward - USB-C Cables will soon be everywhere and all new laptops will start using it, and in fact many already have for over 6 months.
Also, my next new phone (LG G5 or new Note 6) will have USB-C, not lightening. Not all mac users use iPhones.
The third advantage is that if all USB-C ports are in use, and someone needs one more data port, Lightning will be there as an option to provide up to USB 3 speeds. This will be especially valuable on the Retina MacBook which only has 1 USB-C port required for data, & charging. Adding USB audio will not only require an adapter to use a Lightning or 3.5mm headphone, but also a hub to allow more than the headphones to be plugged in.
Why put in a lightening when they could just use another usb-c in it place as its the same size? Doesn't make sense.
They're not going to add a lightening socket on a Macbook.
The fourth advantage is durability. The Lightning connector is a much more resilient connector, and much more protected by Apple than USB-C currently is. As a mobile connector, I prefer it to any other connector I have ever used on a portable device.
While its seems more durable than a usb micro b, I see no strength advantage over usb-c, or thunderbolt, or usb-A.
Overall, Lightning is a much more useful port than the current 3.5mm jack which does one thing -- pass analogue audio signals.
Usb-c even more flexible, but it is not a good audiophile solution nor compatible with 99% of current and future headphones.
Your interest in 3.5mm equipped headphones and current equipment is a personal preference which I don't share. However, all new headphones will likely be hybrid digital products, which will have removable cables for attaching to analogue or digital inputs, or optionally -- wireless - this is pure BS based on nothing. Just because you don't see the need to remove it doesn't really affect whether it will happen. It seems pretty clear at this point Apple will not be the only manufacturer to drop the 3.5mm jack, whether you understand why or not.
Do you just make this BS up as you go? Where is your evidence of anyone dropping the 3.5mm socket on other phones or laptops?
So if you refuse to use digital headphones, then you will need adapters to use most modern equipment after next year. Based on what evidence??
The exception will be devices like desktop Macs, and probably even the larger MacBooks, for a while; in which if theres room, then they will likely maintain the headphone jack for several more years during the transition to wireless. But eventually, all mobile devices are likely to drop the headphone jack (and eventually ports altogether), to make them as small and as light as possible, yet with the maximum of features.