Who needs hard-copy books?

In a Guy Fawkes Day interview with The 26th Story, Seth Godin counsels publishers, "the market [doesn't] care if you make money . . . and the humility that comes from approaching the market that way matters. It's not 'how can the market make me money,' it's 'how can I do things for this market.' Because generally, when you do something for an audience, they repay you."
If publishers really want to do something for their audience, they'll let readers decide how they want their content delivered. Many will choose a PC, Kindle, or Blackberry, especially if the content is free, or very cheap. But some will choose a hard-copy book, and not just temporarily. Here are some types of people who will continue to demand print:
Older readers. Nobody likes a product that has a steep learning curve. That's why nobody except computer geeks bought computers until Apple introduced the GUI. People who learned to read print don't want to learn a whole new skill set just so they can keep reading. To be blunt, this market segment gets smaller every year, but publishers can't ignore them because they've got money to spend (or did until a couple of months ago).
Collectors. Collecting souvenirs is a basic human trait, and Godin himself classified printed books as souvenirs when he spoke at the 2008 Tools of Change conference. And some people stock their homes and offices with printed books so they can look smart (nothing says noveau-riche dimwit like a big fancy house with no visible books).
Print aficionados. My wife is an avid reader. She's not particularly interested in collecting books--she borrows many of them from the public library--she just likes the look and feel of ink on paper, and there's a lot more like her. Publishers won't go broke offering customers a choice. That's why they have electric shavers and razor blades in the same aisle at the drugstore.
The poor. Older readers, collectors, and print aficionados will suck up the higher unit cost of hard-copy books as publishers print fewer of them. But many Americans read print because they can't afford a PC or a Kindle, or monthly Internet access fees. These people will be locked in a permanent knowledge underclass if books and periodicals aren't available through schools, libraries, and hand-me-down copies. Who will make it worthwhile for publishers to keep serving this audience?