It’s still not clear when we will get macOS Catalina, but it can't be far off. There are significant changes with this year's Mac update, including the fact that Catalina will no longer not support 32-bit applications. That means after you install the update, you may find some applications no longer work.
That is information you will want to have before pressing the Install button and not after. Fortunately, St. Clair Software, the same team behind DefaultFolders X, has a great app called Go64 that you can download and run today. It will give you an updated list of currently installed 32-bit applications on your Mac. I have several.
Some of these apps are old and probably not going to get updated, and others are perhaps in the process of getting their 64-bit update now. Forewarned is forarmed. If you intend to update your Mac to Catalina, take a good look at your existing 32-bit applications today.