that is right, "bon" means that the person wants to finish by concluding sg, or to change the subject of conversation. you conclude with "salut" or "en clair [...]",... It can be used when you want to make something clear. Not always to say goodbye so! It can mean "so" or "bref" or "anyway". There is not only one meaning, it is a passkey word in French.

A: well, hey Cora B: bye, meet you tomorrow C: meet you tomorrow ("bon" could mean well, right, nice etc etc depending on what the user meant)