Won't most apps use way more .net stuff than core? Mono was a way to run dotnet apps on Linux, killing it meant killing cross platform support for modern dotnet desktop apps?
Anything that was in the old .net that isn’t in core today won’t ever be.
Then there’s stuff that was missing in the earlier versions of core that existed in old dotnet. Some of it they later realised was useful for newer apps or apps migrated to core. These pieces were ported over by Microsoft or replaced by 3rd party implementations (e.g. avalonia for xplat ui).
(.net core is actually officially just .net, they dropped the core from the name)
What are those Desktop apps you speak of?
Clearly, everything is a command-line backend pipeline in container with a web UI.
And everything that isn't can be easily deprecated. /s