When expressing that something is unlikely to happen, instead of saying "by a long shot," you can use various synonyms that carry the same connotation. These include "far-fetched," "implausible," "unthinkable," "out of the question," and "beyond the realm of possibility." If something is not even close to being probable, you can say it is "nearly impossible," "highly unlikely," or "remote." Alternatively, if you want to emphasize that there is no chance for something to happen, you can use phrases like "no way," "not a chance," or "not in a million years." Regardless of which alternative phrase you choose, the idea remains that something is very unlikely to occur.