Speaking of 3D Touch, Victor Baro has put together some examples of how the technology can be used to build custom controls on iOS 9:

Since I discovered 3D Touch, I have been thinking about new ways of interacting with the content. Peek & pop is a great interaction; but what I really want is to create my own controls.

We need to take into account that, because 3D touch is only available in iPhone 6S and 6S Plus, no action should be completed just by using this feature. The user should be able to achieve any action without using 3D touch (just like peek & pop does), and 3D touch should only provide an extra level of interaction.

It’s a technical read, but make sure to check out the demo videos. As 3D Touch trickles down to Apple’s entire lineup over the coming years, it seems obvious that these new types of interactions will become the new default.