The phrase "are in offing" means that something is about to happen or is likely to happen in the near future. The antonyms for this phrase would be related to things that are not going to happen, or that have no chance of happening. These include words like "unlikely," "impossible," "doubtful," and "uncertain." Other possible antonyms might include "postponed," "delayed," or "canceled." It's important to note that not all of these antonyms are exact opposites of the phrase "are in offing," but they are all related to the idea of things not happening when they are expected.