Not saying I think this will happen but what if Apple shifted the iPhone launch into what has traditionally been the iPod date? They're already struggling to make that particular event shine as, let's face it, we can take a damn good guess at the next iPod Touch from the iPhone specs and the iPod Classic is probably not going to see a vast amount of changes. If they DID move iPhone to September we'd have:
March / April - iPad launch window, ideally early April to ensure it's far enough from Christmas not to stop people buying them for that holiday
May - Filling initial iPad demand and stabalizing supply chain
June - WWDC for iOS preview to developers, ideally on both iPad and existing iPhone hardware
July and August - traditionally slow tech months anyway, focus on easing any remaining iPad supply issues and getting through the Back to School promos while building up stocks of new iOS devices for...
September - Launch iOS alongside new iPhone and iPod Touch. Generate renewed interest in iPad with all new features.
October - Get the initial demand for both new devices dealt with and start filling sales channels for...
November / December - Christmas rush. 'Nuff said.
January / February - Traditionally slow tech period as everything recovers from Christmas, start shifting iPad production to new units for March / April launch.
There's a LOT of good things to be said about that timetable and lets Apple focus on a single iOS introduction at a time. Will it happen? Only Apple know that for certain but it wouldn't surprise me. After all the iPhone 4 isn't really under any serious pressure right now at the high end (yes, Android is selling but it doesn't seem to be taking anything away from the iPhone so Apple won't really care), iOS 4.3 is a nice, mature product that consumers don't seem to be in any rush to get off and the iPad is so far ahead of any other consumer tablet right now it's not even funny so if they're thinking of doing a shift like this, now might be a very good time.