The old-school headphone jack probably needs to go. Devices need to be simplified to use fewer ports as they get more compact and are distilled down to a more pure wireless and software on glass experience. My only problem with this is that Apple is not using a universal standard. People listen to headphones on lots of different devices. We shouldn't have to carry around adapters for each device, or buy different headphones for different devices.
I think USB-C is a pretty good standard to replace the lightning connector. It's more durable than old USB standards, can carry digital audio signals, can carry digital video signals, and wouldn't need an adapter with future devices using it as a standard across the industry. You could just plug your iPhone into a monitor or TV, or plug a flash drive into it, or a card reader, or whatever else. There would be power cords that support it everywhere. I think Lightning is probably slightly more sturdy since it has a thicker metal piece, but the tradeoff is that the contacts are better protected on USB-C. Lightning was created because USB ports were flimsy, non-reversible, and couldn't carry things like video signals. USB-C addresses just about all of those concerns.
The only issue for Apple is the whole MFi program. I think they could still enforce it with some kind of handshake from the device over USB, right? As it stands now, people still make non-MFi lightning accessories without their approval. So this shouldn't change a whole lot. The people who want official accessories will still buy the thing that has the special seal of approval. Everyone else will still buy the $2 cord from Amazon which may or may not burn down their entire house.
This all being said, removing the headphone jack doesn't really concern me personally because I mostly use headphones with my iPad watching videos, or when listening to music on my iMac at work. Sure they might come for those devices at some point, but I'm good for a while. And the headphones I do own aren't crazy expensive. The main thing that affects me is the price of their stock after they reveal an iPhone that looks mostly the same and has a controversial port removal scandal going on. Pretty sure I'm cashing out in early September if they make any decent gains between now and then.