First off - this is a shot in the dark. I have no reason to believe Apple would ever do this.
A mid-year release cycle for Apple would do a few things, and I think help keep the momentum from some excellent hardware without releasing a new phone, hopefully tied to a timeframe with the new iPad this Spring. Apple has gotten a lot of criticism for a lack of new features in iOS 6, and this could solve a lot of problems instead of waiting a full year for new hardware to release with.
There are plenty of new features Apple could introduce without the need for new hardware - things like actionable notifications, live-icons, etc.
Oh, and maybe a great time for an updated batch of Maps data and Siri functionality?
I think you all know the things you would want in a new version of iOS, but what do you think - strategically - about Apple doing a 6.5 release midyear without new iPhone hardware?