Apple files a ton of patents. While some of those ideas come to fruition and make the world a better place, most are just the company hedging its bets on every damn idea someone at the company sketches on a napkin. So don't hold your breath for an iPhone with a hinge.
The first iPhone was a pain in the arse to open and I've never been able to get one back together without warping the metal casing. Every iPhone after that has been a breeze to rip apart and put back together. As long as you have the right tools, you can pry one open without any real effort. Just ask the folks over at iFixit. They've built a business out of opening the iPhone.
If you've ever taken an iPhone to the Apple store you know exactly how much actual "repairing" they do. If you have a problem they hand you a new iPhone and send you on your way. So the idea that a hinge will expedite any sort of repair seems misguided. But hey, if they want add a hinge so your iPhone looks like a car when it's being worked on I'll be sure to buy a tiny drop light. [Patently Apple]