Hi PBrowning . This is a rumor that has been created from some confusing comments from Microsoft in the past few years.
tldr; - OneNote is not going away. This includes online (web) apps and desktop apps (Windows / Mac).
Long version:
In April 2018, Microsoft announced that OneNote 2016 was going away. They received a lot of feedback from people using OneNote and about 18 months later they announced it was staying.
SO, we have two OneNote desktop apps for Windows 10 - "OneNote 2016/2019" included with the other Office apps and "OneNote for Windows 10" which is available through the Microsoft Store on Windows 10.
There's also OneNote for Mac, OneNote for Android, OneNote for IOS, and OneNote web sites.