The antonyms for the phrase "becoming a fact" include "remaining theoretical," "staying hypothetical," and "remaining uncertain." These antonyms suggest a state of unproven or speculative ideas. When something remains theoretical, it means that it has not yet been proven or tested, and its realization is not guaranteed. Staying hypothetical is also similar, implying that something is still just a speculation or a theory. Lastly, remaining uncertain suggests a state of ambiguity or doubt, where the outcome is unknown and could go either way. Using these antonyms can help to describe situations that are still in the early stages of development or have yet to materialize.