The future of Interaction
I like to see design as inventing tools that Amplify human abilities , hammers amplify the force we can exert on a nail, glasses amplify our ability to see and mobile phones amplify our ability to communicate over great distance. The interface of the hammer is its handle and affords the user how to hold and control the device. The user has one continuous degree of freedom, holding the hammer near the head allows for precise control, holding the hammer near the back allows for more powerful blows. In the case of the mobile phone the user has to make more decisions before the functionality can be accessed. In modern phones the user only gets two degrees of freedom on a screen to interface with this functionality. There is a mismatch with the degrees freedom used for interaction and the amount of functionalities that needs to be controlled.
The tools that are designed today have an every increasing amount of functionality because of how technology evolves  and because of the desire of consumers to cluster previously unrelated functionality in a single device. While functionality per device keeps on growing the way we interface with this functionality does not change to the same extend. This makes our tools harder to understand and use.
In order to make the tools of the future more comprehendible we need to change 2 things. Firstly We need to stop moving our product interactions to apps on smart phones and create interfaces that are physically located on the devices that contain the functionality.
Secondly, interfaces for (digital) functionality rely heavily on the cognitive abilities of their users, these abilities are inherently limited. It therefore makes sense to lessen the load on our cognitive abilities by also involving our perceptual and motor skills in interacting with an objects interface. Tangible, rich  and haptic interfaces allow for increased use of our perceptual and motor skills in controlling objects and systems and should therefore replace screen based interactions with products. These interfaces interfaces allow the user more means of expression  and comprehension which in turn reduces the cognitive complexity of the interfaces.
The problem of Emergent Functionality
There is a problem with the tangible, rich and haptic interaction paradigms that is most apparent in a system context. These paradigms do not allow for emerging functionality  to the same extend a screen based interaction, since these interfaces are not as easily updatable. Shape changing interfaces with dynamic affordances might be the answer to the emergent functionality problem .
Some of these Ideas are more then 20 years old but have almost never been successfully commercialised. Instead industry is moving more and more towards apps and screens and away from physicality.
Consumers seem to care more about the flexibility of their digital swiss army knives (aka smartphones) then the rich experiences that were destroyed in the transition. I think it is our duty as designers not to be slaves towards this trend but to instead show consumers realistic alternatives for their interfaces. It is my ambition to create tangible and rich but still marketable solutions for the products of tomorrow.
 Bret Victor - Brief Rant on the future of interaction Design - 2011
 Kevin Kelly - How technology Evolves - 2005
 Stephan Wensveen - Interaction Frogger - 2004
 Tom Djajadiningrat et all - Easy doesn't do it: skill and expression in tangible aesthetics - 2007
 Joep Frens, Kees Overbeeke - Setting the Stage for the Design of Highly Interactive Systems - 2009
 Sean Follmer et all - inForm: dynamic Physical Affordances and Constraints trough Shape and Object Actuation -2013
 Joep Frens - Designing for Rich Interaction - 2006
 Hiroshi Ishii et all - Laying the Foundations for Graspable User Interfaces - 1995