The phrase "taking off as" is often used to describe something that is becoming popular or successful. However, there are several antonyms for this phrase that signify the opposite situation. Some of these antonyms include terms like plummeting, declining, failing, stagnating, or struggling. When something is plummeting, it means its popularity or success is rapidly declining. If something is declining, it might imply a slow and steady decrease in popularity or success. Alternatively, if something is failing, it suggests that an initial attempt at success or popularity has fallen flat. Stagnating implies a lack of growth or development, while struggling suggests that something is facing constant obstacles in reaching success or popularity.