At a high level that’s literally the first idea that came to me for a creaseless design. The ultra thin hinge becomes a huge stress point, but flip phones prove it’s still reasonable.

However, the real issue is implementation. Trying to get the screen rigid over a void and fit all the components into a very confined space. IMO, this is what should be patentable not the idea of a void. Aka. Is it a viable phone or just a nifty demo.

PS: And looking at the patent that’s actually a big part of it. Their hinge design is has some very interesting tradeoffs, which might make this viable.