While in theory a folding phone might protect the screen from falls more, I suspect making a sturdy case for it might be hard. I also wonder if the hinge might break and then the phone might fall apart easily. Honestly I don't like the way flagship smartphones are so easily breakable nowadays, and this kind of design might make it worse. I know glass backs probably seems more "premium" to some people, but plastic backed phones are typically so much more durable, in my experience at least.