In Europe plenty of 4 door saloons/sedans receive this kind of 5 door hatch/'fast back' treatment and have done for a long time... best sellers such as the ford Mondeo and Vauxhall/Opel Vectra have been more popular with the tail hatch than as a 4 door saloon or full on estate/wagon/tourer. I guess this is something that is not common in the US.
Personally, I think the shape can be done quite well...