Will Catalina users be able to stubbornly cling to iTunes?
The page you've linked specially states that 12.8 is available for "previous versions of macOS". I think it is clear that iTunes on Catalina is not an intended configuration, nor is it probably officially supported by Apple.
Indeed if you try to install iTunes 12 on the Catalina GM, you'll be informed that it is incompatible software - and won't install.
If you really, really want to run iTunes on Catalina, you can use this script to allow installation.