While 2010 showed tremendous growth in the eBook market, 2011 could be even bigger. While many of th big Christmas sales figured have yet to be reported, it is safe to say that millions of people received an eBook reader for Christmas and those new owners have started buying books. Barns & Noble reports that they sold over 1 million eBooks on Christmas day alone! When you add this to others like Amazon, it’s easy to see how there would be big post-holiday surge of sales. According to Publisher’s Lunch, there could have been as many as 5 million new electronic book readers out there who are eager to load up their Kindles and Nooks with new titles.

Some say that this trend can’t possibly last. Kelly Gallagher of the publishing research firm Bowker says the e-book surge of the past month isn’t a “sustainable trend”, claiming that sales could flatten this year but might be twice as high as they were in 2010 accounting for 1 out of every 5 books sold. Since the average hardcover costs $15.50, while the average e-book is $8.75 Gallagher claims that “e-books are cannibalizing the print book market.”

Amazon’s Russ Grandinetti disagrees and says that although some best-selling e-books are outselling their print counterparts, “our print business continues to grow. We see e-books as an additive more than a substitute.”

According to USA TODAY’s Best-Selling Books list, eBook versions of the top six books outsold the print versions last week. And of the top 50, 19 had higher eBook than print sales. It’s the first time the top-50 list has had more than two titles in which the e-version outsold print.

No matter how the trend toward eBooks pans out, “it’s good for readers, and reading is good for publishing,” says Scott Lubeck of the Book Industry Study Group.

But business models must change, he says. “It’s sort of like the transition from the horse and buggy to the auto. Some people will get it, some people won’t.”