Honestly, none of this novel foldable-screen stuff is necessary for an e-reader's use case. You don't need a double-wide tablet-sized screen for e-ink. Two e-ink screens with a hinged spine, and a ribbon cable going through the hinge; that was technically doable way back at the original Kindle release. I'm amazed it took this long for someone to have the idea of making their book-replacement show you two pages at once.
I loved the e-ink readers, but they were to small and held too little text on one screen so I usually use a 10' tablet. But a dual screened e-ink reader would be amazing.