If you have your copy of kindlegen, it will continue to work - it is a 32-bit statically linked binary, so as long as your kernel supports 32-bit processes and

If you have your copy of kindlegen, it will continue to work - it is a 32-bit statically linked binary, so as long as your kernel supports 32-bit processes and 32-bit ELF files, you are good to go. That it is available for download changes nothing; it has not been updated for years anyway. The mac version was in worse shape, it was also 32-bit, so it didn't run on Catalina at all.