I actually had the same idea about the swinging cars when i tried to design a more reasonable 4d-concept.
My design was also set like pipeline coaster with 4 seats, 2 back-to-back in each car. Of course it wouldnt be as intense as X or as huge, more like a wild-mouse coaster, but it could do some pretty cool stuff.
Yes, the cars would be able to flip around their horizontal axis simply by means of a counter-weight on the bottom, thats the whole point.
Whats you definition of a 4d? A ride that opens a space-vortex and transfers your molecules in a new dimension?
It can do a lot more than that. It can swing from side to side, under total control.
I don't see them build a real rollercoaster in near future, but I could see a park investing to create a dark ride/themed attraction with that technology.