Will the Kindle Make Books Thinner?

Jim Henley wonders if the Kindle and its brethren won't reverse the trend towards thicker and thicker books:

I understand the impulse on the supply side toward thick books: I myself have witnessed bookstore shoppers choose one book over the other because "this one's thicker." (Said out loud in so many words.) And I witnessed a shift in mass-market printing strategies toward using thicker paper, bigger fonts and wider margins. Compare a mass-market paperback from the 1960 or 1970s with a reprint of the same title from the 1980s or later and the difference is stunning. In the earlier era, the publisher was plainly trying to keep the physical size down; in the later era, puffing the same text up like a blowfish.

What interests me is how the ebook era will affect book lengths. Right now, all ebooks look "the same size" on the (virtual) shelf. The Kindle store gives you a "print length" but, at least for me, that's an abstract fact I take little notice of. Baen Books successful Webscriptions store doesn't even do that. Perhaps one day ebook vendors will list a book's word-count instead, but I don't think that will make as much impression on shoppers as a physical package's relative bulk does. Also, my Kindle's progress bar is relative rather than absolute. No matter how long the text, the progress track runs the width of the screen. If you're a third of the way through a 100,000 word book, the progress bar extends a third of the way across the screen. If you're a third of the way through a 200,000 word book, likewise.

Every change in "printing" technology/economics has affected the forms of literature. This one will too.

On the one hand, it will be nice that books no longer have to sell themselves by adding "doorstop" and "paperweight" functions.  On the other hand, one can imagine it going the other way--longer books are now cheaper to print, and easier to store.  Also, to the extent that ebooks have lower margins, editors will have less time to invest in sweating loquacious writers down to a more appropriate number of words.  I have no doubt that the new technologies will change the forms of literature, but I have no idea how.