Samsung is expected to launch a bunchaton of new hardware at Mobile World Congress the month after next, and according to the latest rumors that includes an E-ink case for their next Galaxy smartphone.
Samsung is widely expected to launch the Galaxy S6 at MWC (leaked metadata points to that conclusion), and according to one Android blog in Poland that's going to include a special case.
According to Android.com.pl, the Galaxy S6 will have a sensor for measure your blood sugar, new lenses for the camera, and most importantly a special case which adds a secondary E-ink screen.
There are no solid details to support this rumor, so there's no way for us to judge its plausibility, but it's not out of the question. I still don't think it's very likely, but the reason I'm not dismissing this rumor out of hand is that I know of a E-ink case for a Samsung smartphone - only it's not made by Samsung.
I got to play with it at CES 2014 a few months later. It was a fun gadget; limited to only a single smartphone model but still fun.
Pocketbook hasn't released any other models, but I do know that they had intended to do so, and it is entirely possible that Samsung will show off a new CoverReader in March.