Very interesting. I’m currently using a case by the same manufacturer on my 4S. It’s not unusual for speculative case makers to release products for iPhones that haven’t been announced yet- it’s a fairly low cost gamble if they have received credible specs on the new phone’s dimensions.
One rumor that continues to gain traction is that Apple will stop selling any previous generation phones once their new lineup ships this fall. The iPhone 5, 4S, and 4 will be retired, and the iPhone 6 (or 5S) will sell alongside the less expensive 5C, which is said to be in a curved plastic case that comes in colors. Apple will then be able to retire the 30 pin connector (iPod classic notwithstanding) and improve their profit margins with these all-new devices.