I think ebooks will change the landscape less in the short term than Charles is supposing. The idea of 'genre' is a powerful one with a lot of momentum, and not a little utility independent of physical organization of books. Genre will continue to be a useful way for retailers to partition the power law to maximize sales.

I'm also hopeful that the growth of ebooks will make the promise of GoodReads or even the good old days of rec.arts.sf.written come true: that 'what you read' will become an ever more viable way to find birds of a feather for both book recommendations and social connections.

One interesting thing is that an e-ink e-book is particularly bad interface with which to find new titles. It's fine for buying something you know you want. But a real, internet connected PC is currently needed. I imagine this situation will get better.