While macOS Mojave brings lots of great new features, it also retires some. The Mail stationery templates are gone. Cover Flow view has been replaced with Gallery View in the Finder. Integration with Facebook and other social networks is gone, most likely for privacy reasons. Back to My Mac has been retired, but all sharing functions like Screen Sharing and File Sharing remain. Warnings that 32-bit apps will soon no longer work with macOS are just warnings, however. Those old apps still work in Mojave.