The phrase "about to happen" can be replaced with a variety of synonyms to convey a similar meaning. Some alternatives include "imminent," which implies that something is likely to occur in the very near future, or "impending," which suggests that an event is looming and could happen at any moment. Other options might include "on the horizon," which implies that there are signs that something is approaching, or "approaching," which simply suggests that an occurrence is coming closer. Regardless of the specific word used, each of these synonyms conveys the sense that something significant is about to occur.