Good piece by Seth Weintraub running down the details on USB-C. As for this question:
By next year, I would expect all new Macs to have USB Type C. I would expect Apple displays (if they keep doing displays) to be USB-Type C based. I would expect Lightning cables and most of the industry to move that direction too. The question in my mind is: Will Apple keep Lightning or are you looking at the next iPhone connector as well?
I think the answer is probably “No, Apple is not going to switch the iPhone and iPad to USB-C”. I think Lightning is a more elegant design, including being slightly thinner. And I think Apple likes having a proprietary port on iOS devices.
But, if they did move iOS devices to USB-C, then you could charge your iOS devices and MacBook with the same cable. And within a few years, all phones and tablets from all companies would charge using the same standard.
(Via Daring Fireball.)