The critical change in macOS 10.15 (we won't know what to call it until the WWDC in June) is the deletion/removal of all the 32 bit APIs (Application Program Interface) that connect the application to the OS and its kernel. Those APIs
HAVE NOT BEEN DELETED FROM MOJAVE so 32 bit apps should continue to work and that includes printer drivers. The key is
EXECUTABLES as they are the users of APIs. Depending on the developer, printer drivers may, or may NOT, have an executable component. Often the executable component may be an installer, uninstaller, or service application included with the printer installation.
- Run the System Information app in your Utilities folder,
- Click on Software > Applications
- click on the column labeled 64 bit
- click on the sort arrow so that it points ^
You will see a list of all the non-64 bit executables on your system. (
NOTE: this is a more complete list than is generated by Etrecheck)
At the moment I have an app named "InkServer" on my system another named "quicklookd32" and the developer of both is identified as Apple.
There are factors other than 32 bit APIs that can cause a printer driver to quite working. Many of the original APIs have been deprecated and later deleted and their functionality moved to new APIs or merged into existing APIs. The same thing is true of the Unix command line commands that undergird much of the functionality of MacOS. If developers have ceased to maintain their app or driver or have simply been inattentive to the changes, which are typically announced two or three years in advance an upgrade to the OS could make the app/driver non-functional or at least semi-functional. Some printer manufacturers have been noticeably unwilling to support changes for printers that are no longer in production. Even if they sell you a replacement printer for less than the cost of building it, they figure on making it up in sales of the latest and highest priced ink or toner.
