This is some news to be thankful about, and possibly to ring in the new year! A lot of books are now entering the public domain here in the U.S. For 20 years this process was frozen thanks to the Copyright Term Extension Act of 1998 (also known as the Mickey Mouse Protection Act and Sonny Bono Act).
The HathiTrust public domain content, an archive of publicly available books numbering in the millions, has been fairly static for a number of years. However, the number of public domain titles in HathiTrust have increased by 11% (!) and the number of 1923 titles in the public domain jumped by 313%. Keep in mind that this applies to music and songs too! In fact, here is a list of holiday carols that shows which songs are in the public domain. Be sure to check this if you’re making any social videos featuring holiday music.
This appears to be a clear sign of what we have to look forward to in coming years!