People have different use-cases to me, I know, and I attempt to keep that in mind.
However, when I think of 'out of the house tablets', the first use-case that comes to mind is keeping commuters entertained, but they mostly already carry a bag for other items - so can easily accommodate a conventional 9" 3:2 ish tablet (iPad Mini or equivalent).
Another use case is when you're running around a wild west theme park and the UI you need to quickly diagnose a killer robot requires more screen than a phone can give you.
Maybe folding screens will find their place in making a laptop fit into a small handbag instead of a satchel or rucksack? That's the sort of thing Weird Sony have done, back when they still made VAIOs (they made a folding dual screened Android tablet, they made a Windows net book with the screen no taller than the keyboard, heck they even made a Windows XP tablet with the keyboard spilt either side of the screen.)