This was announced in April 2025, but I missed it at the time, so thanks to David for letting me know that The Köln Concert is "among the 25 audio works chosen this year to join the National Recording Registry of the Library of Congress, which preserves works deemed “culturally, historically or aesthetically significant” that are at least 10 years old."

The New York Times has an article about some of the works included in the registry this year.