A phone with size of almost as big as a Tablet (Fold) and as big as a Laptop Screen (Unfold)? Who want to carry that all day?
The only I could think of is by put that "big" thing called phone in a bag. Today Tablet accept SIM Card by the way, go figure.

Mobile Phone can not more bigger than today (21st century) biggest standard.
Remember Motorola StarTAC? A flip phone (clam shell type). It fit in your pants pocket. Maybe if this "new flip phone" as big as that I would consider to buy.