The publishing industry typically waits for the last eight weeks of the year to release blockbuster titles. This is because book sales dramatically increase from 700,000 units sold per week to over 3 million. Companies that are involved in the e-book space normally do not see an influx of sales until after Christmas, but this might be the first year that the digital boom period never came.
Digital books first gained mainstream prominence after the first generation Kindle was released in 2007. e-books went from almost 0% market share to 24% within six years and everyone thought the death of print was inevitable.
The bleak future where all bookstores have gone out of business never occurred and e-book sales have more or less stabilized. The years of double digital growth are over, as the novelty of a new format has clearly waned.
I think that the phenomenon of the e-book sales booming right after Christmas has gone away. This is supported by data produced by Good e-Reader who recently asked 263 users if they bought a single e-book from December 25th to January 1st. 61.6% said no, while 23.19% said that they did.