Here is a link to the latest AutoCar article on the next 911 with rendering.
Looks the same as the current car if you ask me. It will evolve into a more luxurious 2+0 GT and move "upmarket"
The Cayman/Boxster will also move upmarket as a new 4 cylinder entry level
roadster will be developed with VAG (the '356")
The new cars will be bigger, more powerful, more economical, more expensive and not look much different than the current cars.
You can be sure that the new Cayman won't be faster than the entry level Carrera
Next Porsche 911 in detail - Autocar.co.uk