I posted a longer comment about this last night[1], but the short version is: Amazon is clearly much more interested in profiting from content than hardware. That means they want cheap devices that people will take everywhere and read lots of books on. The Kindle DX is less portable (and thus you're less likely to take it on your commute, etc), and its main advantage is for reading PDF's, on which they make money.
So I think it will be an expensive second-class citizen for the forseeable future. It's not in their interest to change that.
> main advantage is for reading PDF's, on which they make money.
I suppose you mean "make no money", assuming PDFs are off-the-net stuff, which is quite likely.
A couple of years ago I got a Kindle DX for technical PDFs, and haven't used it much past the first year - it's not really pleasant to use. It combines the size/weight disadvantage of an iPad 10" (not the upcoming mini ;-) with the slowness and poor resizing of eInk.