Apart from greatly improved power delivery, faster transfer speeds, ability to support pretty much anything (hdmi, networking, thunderbolt and whatnot)? Or the fact that pretty much all new laptops and phones (except apples, yet), cameras, usb-drives and similar come with USB-C now? It's very quickly becoming the new standard, and everyone but apple is on board so far. Sure, Lightning can do a lot too, just not as much.
And no, wireless isn't better. It's good, and becoming better, but you will ALWAYS charge your phone in the area of twice as fast with a cable, probably even faster than that (Meizu just announced a new chargin system that will charge its 3000mAh batteries to 100% in <20 minutes, for example). USB-C straigt to a phone will always have like 10 times the transfer speed advantage over wireless, at least for the forseeable future.
So yes, they are wireless devices and work great as that. But if you want to use a cable, which a lot of people do as it's way faster, why not use the best on the market? That also has the same connector that your computer, camera, printer, android phone and any other peripherals, so you basically just need one type of cable for everything? I highly doubt Apple won't jump on the USB-C train, especially considering how much work they put into developing it.
You'd have to convince me that USB-C is capable of superior power delivery, and faster transfer speed than Lightning is capable. I'm not talking about current implementation of Lightning, but what it's capable of, particularly with respect to the Lightning 2 in the iPadPro. Next, you'll also have to convince me that USB-C is superior to HDMI, networking and "whatnot", over Lightning. Third, I'd like to see mobile TB3. The MB doesn't even have that yet. I also can't imagine why a mobile phone would ever need it. Are there Android mobile phones that support TB3 over USB-C presently? I'd love to see one.
As for the ubiquity of USB-C, well I guess I need more convincing. When a USB-C device, or cable, is available at a 7-11 at 3AM, then I might be convinced. If I had to find a USB-C device, or cable, in my office right now, I'd be looking an awfully long time -- and that's a company of over 5,000 employees.
Again, transfer speeds are irrelevant if the average mobile phone user is not transferring files via a cable -- and I'd wager most aren't. Many people never plug their phones into anything but a charger, and store all of their data in the cloud, if that. And keep in mind, this is exactly what Apple wants people to do. As far as charging, I'd take slower wireless charging throughout the day rather than a quick top off, and no access to power throughout the day because I don't have time to plug it in.
Apple spent a lot of time investing in Lightning, so I don't see them tossing it by the wayside. Yes they spent a lot of time investing in USB-C, but not necessarily for their phones -- but so the Mac didn't get stuck with another kludgy a-symetrical USB-solution. The Mac is not an iPhone, and the iPhone is not a Mac. So far I see no evidence of Apple trying to merge those two. The iPad is as close as that comes, and I don't really see Apple pushing the iPad toward the Mac, if anything the MB suggests the Mac is moving toward the iPad.
But again, this is all going in the wrong direction, because Apple doesn't seem to be interested in a wired, mobile solution, whether Lightning or USB-C. Both leave big, leaky holes in the devices they have to waterproof. Since USB-C is not particularly superior to Lightning, and Apple likely intends to eliminate wires completely at some point, then why not leave Lightning with an installed user base of over a billion customers, until they're ready to remove ports completely.
If you want to argue customers like wires and demand wires, and only want to carry one wire, as the reason Apple will switch to USB-C, then I have to disagree with you and move on, because I don't think that's Apple's goal at all for their mobile devices. And if they haven't demonstrated it painfully enough to everyone by now, the Mac is not the main priority for Apple these days.