Elsewhen is a word that refers to a time other than the present, but few synonyms of the word exists. However，here are some phrases that can be used as a replacement to the word "elsewhen", such as "at some point in the future", "at a later time", or "at a different time". Another way you could rewrite a sentence with "elsewhen" in it is to rephrase it with "elsewhere in time" or "in another time". Despite the lack of synonyms for the word "elsewhen", there are still many ways to describe something happening outside of the present.