By and by is a commonly used phrase that is often used to mean "soon" or "in the near future." However, there are many other ways to express this same idea. For example, you might say "eventually," "before long," or "soon enough" instead. Other options include "in due time," "shortly," "in a little while," or "in the coming days." If you're looking for a more formal phrase, you might consider using "in the fullness of time," while more casual alternatives could include "pretty soon," "in a bit," or "before you know it." All of these synonyms convey the idea that something will happen soon, making them great alternatives to the phrase "by and by".