How Apple is Ending iBook Author, iTunes U

Apple is transitioning iBooks Author to Pages (by July 1, 2020):

📖 https://support.apple.com/en-us/HT211136

There’ll be an import tool in the near future.

Apple is also discontinuing iTunes U (by end of 2021):

🎓 https://support.apple.com/guide/itunesu/welcome/web

There’ll be ClassKit support added to transition to Schoolwork.

Lots more information in those two links.