Social hub would be an awesome refresh to the contacts app. And the web os multitasking seems great but an option to choose either old or new would be great.
One or two of these are very well done. Some of them are nice ideas but poorly implemented. Some are just dumb. For instance, the iOS 7 Concept 4-Inch 2013 video makes iOS look horribly cluttered and the shaking idea would mess up all apps that use the accelerometer.
The first video, however - the app switcher - looks like something Apple would potentially make. One of the few good concept videos ever.
We all know apple wouldn't go past what they Lready have other than just creating more apps