VW has streamline the platforms that they build on; that way, they can use similar parts across multiple vehicle and keep costs down. I don't think; VW would make a car like a beetle that is totally unique unto itself. These days; its all about costs, shared technology and reducing redundant engineering. Check out this article; for the way they are going with platform designs, that can be used across many car models.
Volkswagen's Golf 7 MQB component platform architecture
If you want to see a model that is like a karmann ghia; check out the european model of the scriacco, maybe one day they will let us have one!
: Volkswagen UK
To quote this wikipedia page:
"Volkswagen began work on the car during the early 1970s as the replacement for the aging Karmann Ghia coupe"
http://en.wikipedia.org/wiki/Volkswagen_Scirocco
I was a aircooled beetle/super beetle owner and daily driver from 1987-2000; while I look back at those years with appreciation, I don't miss swapping engines and the lack of all the modern conveniences, that the new modern cars have!
I think from the new beetle on; they just are not the inexpensive cars that the originals were and were not designed to be. I believe a beetle was one of the cheapest cars you could buy at the time (50s through the 70s). If you wanted a car like the original beetle; it would be more in the vein of a VW Polo or UP! Which unfortunately, they don't sell here in the USA; maybe one day they will. Check these cars out; definitely, designed to be inexpensive transporation and excellent mpg! 
Volkswagen Up - Wikipedia, the free encyclopedia
http://www.volkswagen.co.uk/new/up-nf/home
Volkswagen Polo - Wikipedia, the
http://www.volkswagen.co.uk/new/polo-v/homefree encyclopedia
I'm curios; why do you prefer the rear engine design cocept; from a nostalgic point of view or for some other reason?
Volkswagen's Golf 7 MQB component platform architecture
If you want to see a model that is like a karmann ghia; check out the european model of the scriacco, maybe one day they will let us have one!
: Volkswagen UK
To quote this wikipedia page:
"Volkswagen began work on the car during the early 1970s as the replacement for the aging Karmann Ghia coupe"
http://en.wikipedia.org/wiki/Volkswagen_Scirocco
I was a aircooled beetle/super beetle owner and daily driver from 1987-2000; while I look back at those years with appreciation, I don't miss swapping engines and the lack of all the modern conveniences, that the new modern cars have!
Volkswagen Up - Wikipedia, the free encyclopedia
http://www.volkswagen.co.uk/new/up-nf/home
Volkswagen Polo - Wikipedia, the
http://www.volkswagen.co.uk/new/polo-v/homefree encyclopedia
I'm curios; why do you prefer the rear engine design cocept; from a nostalgic point of view or for some other reason?