A comparison between the real Porsche 911 R of 2016 (the car with the two red stripes in the following images) and a concept draft of a 911 (black stripes) tells the whole questionable story of Porsche.
Obviously the concept draft is not a new car body design in its own right. It is based on existing 911 attributes. But first and foremost the draft changes these attributes (Weissach attributes) in the spirit of Erwin Komenda.  – The world commemorates the 50th anniversary of Komenda's death this year. 
The images of the concept draft (a 3D model I tweaked  ) show all the same design version (form) from various perspectives. (Click to enlarge. All large renderings are 1440 x 960px in size, 250K each)
It is obvious I admire the Komenda design and place here criticism against Porsche/ Weissach. The question is: Were they able in half a century since Komenda's death to build a really classic "911" ? – No, they were not.
Along these lines my concept draft is not a dream how an upcoming 911 (or Cayman) should look like. It is "retro" rather, it is what sadly didn't happen in the last 50 years.
What is the problem?
What are the creative problems Porsche and Weissach have?
- The philosophy of the 911 to be rear-engined is interpreted in Weissach (mistakenly) as 'engine beyond the rear axle'. To compensate the resulting rear overhang the car front is over-jacked (with no real purpose except oversized air intakes and coolers ) - last image above.
Porsche knows it. The view angle of teaser images are usually deliberately warping.
- In the original 911 design the shoulder line  draws a bow with full-length body tension. It was deadly to let the line visually sag vapidly in the door segment.
- The initially inclined silhouette is not only prominent from the side view of the car but also from the top view (Porsche 356). For the rear wheels the track is more narrow. – Nowadays the Porsche management directs its designers to change the style to the opposite. The back view has to look fat and martial. From the side view the lines have to rise toward the back (see the bottom line of the side windows).
Alltogether the points above repudiate the foundational principles of Erwin Komenda's 356/ 901 design. Nevertheless still today Porsche benefits from the distant echo of Komenda's genius. (Since 1963 Porsche disavows not only these principles but pretty much Komenda as a person and Komenda's role as the origin of Porsche's car body design - a later copyright demand by the heirs was rejected.)
But in the end it's all about original, sober elegance, inherent in the nature of the designer, instead of factitious car body attributes ordered by a management ("beefy rear view" etc.).  
The essentials of the 356/911 body design
(and the deadly sins to get something else but not a Porsche 911. It seems in Weissach they don't know about these essentials.)
1. The basic silhouette of a flat roundet cone
(and to turn it into a box)
2. The shoulder line as a bow with full-length body tension
(and to turn it into a slack wave)
3. The lines of the car follow an air-flow pattern that clings to the ground
(and to turn the lines into a “dynamic” uplift to the rear end)
4. The profile that signifies acceleration is drop-shaped declining to the rear end
(and to turn it into the opposite, a big-ass design)
The details of form
Comparing the following views of the two cars you could think it's about details or about not more than little changes in some measurements. – It is not. The redesigned car has a different philosophy. It's an absolute different, a principled 911. 
 Janis Joplin (1968) and her Porsche 356 C Cabriolet, the real Porsche, designed by Erwin Komenda (of course except the paint)
 There is no commemorative culture in Germany but at least designaustria commemorated the 50th anniversary of Erwin Komenda's death in a tweet. (The image shows Komenda in 1940.)
Erwin Komenda #PorscheDesigner Zum 50. Todestag. Skizzen, Hintergründe etc.: http://bit.ly/2bvZpQg
 For the purpose of modeling I reactivated a cgi software on my computer I used ten years ago: MODO. (Modo 401 – even today the workflow and the rendered results of a decade-old 3d software version are sheer pleasure.)
 The rationale is, the 4.0-liter-six engine of the GT3 needs big coolers. I disagree. (Some people order a stereo for their coffin.) A well-working cooling system of a car is needless when the car is so ugly you don't take a ride.
(Sadly new technologies like EV do not help Porsche designers to find back on the right way. They always choose ugliness.)
( >>  for more on new technologies )
 Prof. Lutz Fügener provides a striking analysis (left sketch) of the essential design ideas of the 356/ 911 Porsche. But his thesis these ideas are lasting in contemporary Porsche design -irregardless of all fad- is an industry-friendly lie (after all he earns a living from the auto industry). The opposite is true.
 Not in designing street-legal cars anymore but in engine design, in motorsports and racing Porsche's merits stay all the time amazing and incredible.
 Even Daimler follows (not just sober) these principles (the blue marker lines in the yellow box).
 In the industry it's all about the technical details: Can the rear air entrance be placed like this in conjunction with a mid-engine? Where are the intakes for the cooling system? Where is the upper brake lamp? etc. – Granted., all that is not my problem (considering the engine is probably H2 or E).
 Addition on future technologies of transportation:
The management of the German auto industry ignores as always the signs of the times and deceives itself (and us).
Battery-powered cars are not the solution. It is not the point whether there is a loss factor of 1.4 (battery) or 2.8 (fuel cell). Hundreds of millions of battery-powered cars are a catastrophe for mankind. It is nonsense to accelerate and decelerate a 300 kg battery in each car (not to mention how dirty the extraction of lithium, cobalt etc. for millions of EV batteries is).
Power from the electricity grid is today just as dirty as combustion engines are. But in 20 years there will be enough wind parks (not only offshore but stand-alone on the high seas) that can store energy universally usable, that produce hydrogen to superabound.
The truth is, not the end of the combustion engine is the problem, but the days of individual transport are over. The days of car production for individual buyers are over. The billionaires will still drive million-dollar cars, but nearly all other people will own no car at all. They will share their rides in 8 seat vehicles route-managed by AI. There will be no cars parking in the streets anymore. All the parking lots in front of apartment blocks will be empty and a car that's not on the move will be suspect or like a waste.
Audi (mainly controlled by Porsche SE) did set an example how much the EV hype is about deceiving people. Audi will equip e-cars with solar cells to improve the cruising radius. – Of course the surface of a car body collects just enough solar energy to use a power window once per hour (for sure not enough to drive the air conditioner in the sun). But that doesn't matter for the industry. They don't want solutions, they want to sell their cars further on. In PR and relation to public health the auto industry is worse than the tobacco industry.