Apple may or may not be planning on shipping an iPhone model with a 5.5-inch display, but that isn't stopping insider sources from saying it's delayed and won't ship until some time in 2015. Sources claim the rumored device is real, and that production issues will keep Apple from releasing it until next year.
The hold up in getting the 5.5-inch iPhone to market is that Apple can't get batteries thin enough to fit inside the smartphone's redesigned case. News of the reported issue comes courtesy of the Commercial Times out of Taiwan speaking with unnamed sources who claim to have insider information.
Apple hasn't said anything about its future iPhone design plans, although it is likely the company will be releasing a bigger screen model at some point. Going with a 5.5-inch display would make for a pretty big iPhone, and rumors that the bigger model will sport a 4.7-inch screen seem much more plausible.
Going with a 4.7 inch display would let current Retina screen apps scale up gracefully, and would add an extra icon row to the device's home screen. Developers would have to account for the new screen size in their app designs, but most likely wouldn't face the problem Android developers deal with where screen sizes don't scale well from device to device.
What seems more likely is that the perceived delay in the 5.5-inch iPhone is supply chain sources misinterpreting prototype testing as a soon to be shipping product.