That’s an informative preprint. I guess how predictive the immune system is, depends on the stimuli. After a brief read, I believe the preprint shows that antibodies of hybrid immunity (natural infection + mRNA vaccination) should still be effective against future variants of SARS-CoV-2. But either one form of immunity by itself seems to be easily defeated with just 20 mutations, although I think getting such 20 mutations in the right order would also be difficult for the virus to achieve.