eInk readers are not competing with tablets. They compete with paper books. If kindles get cheap enough to manufacture, 5 to 10 years from now, Amazon will send you one for free whenever you want. Hell, they'll send it to you even if you don't want it, AOL-style. Because the content is king -- it will be the really expensive part. And when your iPadXV have two weeks battery time, kindle equivalent will just stay charged forever.
Don't get me wrong. I HATED CRTs and LOVED LCDs since day one. But for reading 5-10 hours in a row, eInks are really better than LCDs/OLEDs and for that reason, and for the facts that they are cheaper, that readers extremely dislike not knowing how the book ends [and having nothing to read] during a long trip, I think the eInk product is here to stay, with a different market from LCDs/OLEDs, sure.