This will keep my 2012 iMac alive if It’s supported. I have a new 12.9” iPad Pro which is my main computer. But sometimes I like to sit at my desk. I have fewer and fewer reasons to keep my iMac around but being able to use my iPad Pro with it as both a second screen and ask an input device with Pencil, really makes keeping a Mac worthwhile.
It's being billed as a macOS Catalina feature, and it looks like you're supported: https://www.apple.com/macos/catalina-preview/#compatibility