9to5Mac reports that it has received word from reliable source Mr. X that Apple is experiencing constrained stocks of the iPhone 4 bumper, suggesting that a discontinuation of the bumper could signal a redesigned iPhone 5 or some other change that would require a modified bumper. While a number of parts from a so-called "iPhone 4S" nearly identical to the iPhone 4 have surfaced, there has been little evidence beyond third-party case designs supporting the introduction of a new form factor for the next-generation iPhone.
With Apple apparently set to discontinue the Bumper, the next iPhone may require an updated Bumper or may even feature an all new design. Of course, there is also the possibility that Apple has simply decided to discontinue the Bumper but still retain the iPhone 4 design.
One other possibility is that Apple may be retaining the iPhone 4 bumper but updating its packaging to reflect compatibility with both the iPhone 4 and an iPhone 4S/5 sharing the same form factor. Such a packaging change could result in briefly constrained supplies of the bumper as Apple transitions into the release of the new iPhone.