By the time Itachi will preapre Izanami, Ma ans Pa would have paralyzed Itachi with Sound Frog Genjutsu and Jiraya would have impaled Itachi with Stone sword.
(Jiraiya doesn't need to be in sage mode for sound frog genjutsu. Ma and Pa will perform it. No sage mode needed.)

(Jiraiya doesn't need to be in sage mode for sound frog genjutsu. Ma and Pa will perform it. No sage mode needed.)