We've surely all seen this day coming - the day when our textbooks become obsolete. Not just in the sense that they are old or outdated, but obsolete as in GONE - we don't need them any more.
I think that, theoretically, we could teach courses now without texts, but that would be a pretty big leap for some people who are still not comfortable with the technology. However, comfortable or not, I think that day is coming - and it will arrive more quickly than we probably ever guessed.
Many teachers already rely heavily on web resources to supplement their texts. In some cases the web IS already the text - the teacher must be a critical reader, compiler, and organizer of a wide range of information - but it is completely possible to put together a rich course curriculum this way.
A year or so ago I became aware of a site called Connexions. People (educators mostly) can contribute and freely use all of the content there. It is set up so that it is mostly scholarly in nature and meant to be used as a textbook type resource comprised of "modules". When it was first developed, there were were very few such sites of that magnitude. However, during the past couple of years, these types of shared sites have exploded. The content - and most of it very good content - is free and there for the taking.
A good example I recently heard about is ushistory.org. Their website has expanded considerably since first put up in 1995 and serves approximately 3 million page views monthly to almost 1 million visitors. The site receives approximately 22 million hits monthly.
Their latest addition is the U.S. History Online Textbook, which includes 60 chapters "From Pre-Columbian to the New Millenium".
This is a well-reviewed resource, and quite frankly, I have trouble seeing why schools and districts strapped for cash would be dishing out $60 for a quickly outdated textbook when all of this is FREE FREE FREE!
The current economic conditions may push schools and districts in this direction faster than any technology initiative ever could!