Cases that cover or protect the home button would obviously cause problems with Touch ID and cases that go too close to the edge of the screen are going to cause problems with iOS 7 whether it's on a 5S or a 5.
99% of the third party 5 cases will be fine. Take a look at the new 5S Apple leather cases and check out the detail. They are extremely tight fitting and compatible for both 5 and 5S.
I think a better guarantee would be all 5s cases will work for the 5. Some 5 cases will work if they have a large cutout for the camera to begin with. Obviously, the bumper cases will work like Element.
I think a better guarantee would be all 5s cases will work for the 5. Some 5 cases will work if they have a large cutout for the camera to begin with. Obviously, the bumper cases will work like Element.