I suspect we're only a year or two from the first color e-paper devices. A quick Google search shows there's plenty of research ongoing.
Yeah I'm interested in that, and I am glad to see its in development. But I am so glad I don't have to wait. For reading, Color is so important for anything that mixes pure text with visual elements, and there is so much of that out there.
I mean for myself thats magazines (of all types), newspapers and comics all told about half to a 2/3rd of my reading.
And for those with children, or those in college or school with almost all text books using color today. Its a huge part of the reading landscape.