macOS Catalina will turn iTunes into Music and add Podcasts and Apple TV apps. This means that media file locations will be a bit different (via Kirkville).
Catalina Media File Locations
These locations were discovered in the developer beta of macOS Catalina, so it’s possible they may change in the future.
- Music: Default location is ~/Music
- Apple TV: For TV shows and movies, the default location will be ~/Movies. Music videos will stay in the Music app at ~/Music.
- Podcasts: These will be stored in a cache folder in ~/Library/Group Containers/243LU875E5.groups.com.apple.podcasts.
- Books: Ever since iBooks became Apple Books, ebooks and audiobooks are stored in ~/Library/Containers/com.apple.BKAgentService/Data/Documents/iBooks/Books.
When you upgrade to macOS Catalina, the Music and Apple TV apps will remember the location of your media, and let you choose the location for its media folders. This means you could store the media folders on external storage.