As a real-world illustration of the whole situation, I recalled last night, when I went to Borders. Having read a wonderful book (see yesterday's post for my gushing endorsement of Dog On It) on my Kindle, I wanted to buy a print copy of it for my father's birthday present. There I was in the bookstore trying to find a print book on the shelf when I had an ebook copy in my purse, on my Kindle (which I always have with me). It occurred to me as the clerk helped me find the store's last remaining copy, that I had brought the enemy into Borders; to Borders, I might as well have had a bomb in my purse because the Kindle takes them out of the book business picture entirely. When I realized I might have not been able to buy a copy of the book if the store had run out, I was reminded that ebooks never run out.
So, I think the librarian is closer to the truth. With ebooks, it's not the authors who will lose out, it's the people who work at book stores. I don't think bookstores will go away, but I think they will shrink as eReaders become more common.