It is kind of early to assume that all it is, is tuned golf R. A stock mk7 R probably is not capable of 400 hp unless you get a bigger turbo. Plus the exterior bits and the bigger brakes and all the other goodies make it totally worth it IMO.
It has been stated by one of VWs officials...I watched a video on it...was at the convention that pic is from...he stated its a tuned R engine to prove the engines potential...still a concept car for now though...but he gave hints of the possibilty it may be released