Apple STICKS to their major plans / release schedules. They don't care about what competitors are doing. I believe they are rarely surprised. Superhuman? No. Infallible? No. Confident in themselves and meticulous in their planning/execution? Absolutely.
Apple's invitations for WWDC said the future of Mac OS X and iOS will be the focus. So, why would Apple not also show off the new hardware that will take optimal advantage of the new software?!
iPhone 5 WILL be revealed at WWDC and avail for purchase very end of 3rd week of June or sometime during 4th week.
iOS 5 will be previewed at WWDC, though does not need to be available by iPhone 5's release.
Rather, iOS 5 will likely be released at same time as Lion (also previewed at WWDC) later in the summer.
Finally, I bet Apple TV running iOS 5 will also be shown with ability to access App Store winning the battle for the living room.
We've heard rumors of a metal back for iPhone 5...I'll also bet iPhone 5's metal back and frame is made using alloys from LiquidMetal...have we all forgotten that little licensing deal? Thin, lightweight but extraordinarily durable. Steve will be able to once again declare it is the thinnest, lightest phone available...beating their own previously released product once again.
After WWDC, you're welcome to slam away if I'm wrong. The only question I have remaining...besides having maybe slightly better cameras and slightly faster speed, what else could they possibly build into the iPhone to make it magically amazing and a must have for iPhone 4 owners?! Also, when's the iCar coming with an augmented reality windshield for weather, traffic, and navigation? ;-)