IMO the most suitable use scenario would be one of those large screen family entertainment devices, a 17"/18" screen but with mediocre performance. In that case the screen itself could be folded with an externally magnetically attached keyboard that's the size of the screen folded. The benefit would be, as most fold screen devices, carrying a large screen around with you that's much more compact than the non-folding screen of the same viewing size.

Aren't most conventional laptops (other than tablets with keyboard accessories) "foldable"? :)

If you are looking to do away with keyboard (or introduce touch keyboard, ugh), then we are not looking at a laptop. If you instead want a multiply-foldable laptop, that might be weird with the technology of today.