The antonyms for the phrase "developing in to" can vary depending on the context. In some scenarios, words like "shrinking," "collapsing," or "deteriorating" could be considered antonyms. These words suggest a movement away from growth or progression towards a negative outcome. Another set of antonyms may include "stagnant," "unchanging," or "static," which imply a lack of growth or change altogether. Yet another set could include "unraveling," "undoing," or "falling apart," which imply a reversal of progress or a regression to a previous state. In any case, antonyms for "developing in to" suggest a movement away from growth and progress, towards stagnancy or decline.