If dehumanization occurs, and people then counter that phenomenon, new words and new meanings will appear naturally just like they always have. Old words will stop being employed. There will still be confusion for a while but it's never really a significant problem. Semantic differences are a symptom of fundamental disagreements rather than a cause.
Look at the word "alt-right" for instance: it filled a need, appeared quickly, was initially criticized as a euphemism but rapidly took on more specific and non-euphemistic meaning. For the younger generations, calling anyone left-wing a communist in the way you describe is already hilariously passé and associated with boomers.