For me, it would be a way to fit them into your pocket easier and safer.
I already do this carry my Voyage in my pocket (with a case) but it is marginal. A 7" Oasis is too big (more square than rectangle) for that but I do like the screen size. If they built one that has a very durable back and sides and that folds in half to fit in my pockets easier and act as its own case I would like to try it. BUT, it would need to have a screen as good as the Voyage or Oasis (flat, good lighting, etc.) or it wouldn't be worth it. The screen is why I have an e-reader and compromising on that isn't something I want to do; it needs to be as good as or better than the Voyage/Oasis is now overall.
(BTW, the "similar threads" for this thread are interesting. In
2014 we were asking "do you think we will have foldable displays in the next 5 years?" Only a couple people really wanted to hazard an opinion and no one chimed in with "YES it will be" or we could give them some kudos. There was one person who said "I'd buy that instantly.")