Will Catalina users be able to stubbornly cling to iTunes? iTunes won't be bundled with Catalina.  A user of the beta has identified some serious deficiencies in the replacement.  I don’t argue with the consensus that iTunes is a mess, but some of the disappearing features are valuable.

The “announcement” (aka “marketing”) says that iTunes 12.8 can be used with “OS X version 10.10.5 or later” which technically implies it will continue to be usable.  But I’m skeptical.
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.