How big is the market?
There's a lot of people who aren't regular readers. People who only read a book 3 or 4 books a year aren't likely to queue up to purchase an expensive reader, unless it offers some compelling advantage. Many of the people who buy a couple of books a week have already switched to the Kindle for it's obvious convenience.
As someone who has gone from being a couple of books a week to a couple of books a year reader (I spend much more of my time on "ephemeral" reading these days - blogs, the Register, newspapers, magazines) I can't see myself purchasing a dedicated e-reader. I expect to be using a tablet device to access the web content that takes up more and more of my reading time, but it will be a general purpose tablet, rather than a dedicated reader.
I can see the 50USD/30GBP e-reader being sold as a "must give" Christmas present in the next couple of years, but I don't think they'll be bought by the readers themselves, so they'll be built to price, rather than function.