updated 04:31 pm EDT, Mon June 2, 2014
Signature device was already feature-limited
Once iOS 8 launches this fall, Apple will officially drop compatibility with the iPhone 4. The information was touched on just briefly during today's WWDC keynote in the form of a slide. The oldest compatible iPhone will thus become the iPhone 4S; for iPads the minimum will again be the iPad 2, while for iPod touches it will be the fifth-generation model.
The change was expected insofar as the iPhone 4 has already been struggling with iOS 7. The release of v7.1 alleivated some performance problems, but the device still lacks support for features that are now de facto on most iOS hardware, like AirDrop and Siri. It's even incapable of some of iOS 7's visual effects.
The iPhone 4 is in some ways Apple's most recognized device. It helped expand the iPhone's reach in the US and internationally, and created the design language used in every subsequent iPhone. Even the 4.7-inch iPhone 6 -- likely to ship with iOS 8 onboard -- is expected to keep at least some elements intact.