As computers and CFD take over more and more of design duties, all of the car manufacturers will have the same data that will drive the shape of their cars. Thusly, all the cars will continue to look more and more alike. There will always be hold outs and exotics pushing the design limits or creating unique shapes, but for the mass produced stuff, it will all meld into one blob indistinguishable from another at an ever-increasing rate.