Being out of date is not always a negative.
I imagine the usefulness of 6 inch eInk readers for reading news could eventually decline, such as if we lost very different kinds of newspaper support provided by calibre and Amazon/B&N. It would be comparable to what happened to Palm PDA's when AvantGo.com news support died.
But it would take a lot for today's eReaders to become obsolete for reading books. There would have to be some great advance in DRM that may be technically impossible and won't come soon. And if -- and I know this is controversial --
Mike Shatzkin is right about the future of publishing, I may not want to read many books published in the 2020's.
If I live long enough, I don't see any reason why I shouldn't be using the same kind of reader twenty years from now, buying good condition used devices when mine wear out.
I didn't switch from black and white to color, in movies, television, or computers, of my own will. Maybe this time I will just say no.
I've already said no to current music, although
Robert Lopez isn't bad.