YOU SAID:

is it unlikely that this phrase will ever be the right secret code

INTO JAPANESE

このフレーズが正しい秘密コードになることはまずありません

BACK INTO ENGLISH

It is unlikely that this phrase will be the correct secret code

INTO JAPANESE

このフレーズが正しい秘密コードになることは考えにくい

BACK INTO ENGLISH

It is unlikely that this phrase will be the correct secret code