Antonyms for the phrase "as case may be" would include phrases or words that indicate a specific and predetermined outcome or course of action. Some possible antonyms for this phrase could include "in any event," "without fail," "determinedly," or "unambiguously." Other possible antonyms could include words or phrases that indicate a single or prescribed course of action, such as "absolutely," "conclusively," "definitely," or "indisputably." In contrast to the phrase "as case may be," these antonyms convey a sense of clarity and finality, indicating that a specific outcome or action is certain to occur.