It would be a catastrophe for sure, but there are some reasons to be hopeful:
Researchers have been studying this bug for awhile and human vaccines could be ramped up more quickly than with COVID.
Further, there are specific mutations that would be key for rapid human-human spread and the variant infecting these cattle don’t have those mutations (yet).
Cattle are not as good a transition species to humans as, for example, pigs. So while we should be watching this, it’s not quite as alarming as it could be.