The developers of the WWDC app have no insider-knowledge communication to the team who are responsible for making iOS 7. It is possible that somebody told them to design the WWDC app in a manner that replicates iOS 7’s look, but this is by no means a certainty.
Of course, iOS 7’s design is going to change and is going to be ‘flatter’. This has been reported by a myriad of people in the last few months. The design of the WWDC app though, shouldn’t be relied on as a foreshadow for next week’s unveiling. For instance, the WWDC 2012 app had an inexplicable silver theme.
If you want to do some fruitful speculation, I’d look at the black-outs in the schedule, as Panzarino has done.