As far as I understand, there's no way to get these bundles to work on Catalina (the next macOS release, 10.15). Also, every Mac user will be nudged to upgrade the OS (and so they do) and new Macs won't be able to boot older macOS releases.
I hope Apple will care enough + offer ways to open source projects to keep supporting macOS. They do offer developer accounts free of charge (for non profits) already, though.