Basically, a scissor switch, but the scissor arms would be actuating a spring going from left to right, and the rubber dome wouldn't be there.
The other issue with transverse buckling spring is, it's quite thick when in use, and relies on a mechanism to lower the keys into a storage position... which requires a linkage from the screen hinge to the keyboard. IBM did that in the mid-90's on a lot of their products ANYWAY, for slanting the keyboard when the screen was raised, or the ThinkPad 701's butterfly keyboard, but nobody does that now, AFAIK.
However, the patent says that one goal was to create a lower profile keyboard (when stored) than the scissor switch+rubber dome boards that were in use, while still giving full tactile response and a full stroke. This tells me that the technology may still be relevant...