why i think that ?? Well Amaterasu wouldn't do anything to minato since he has FTG, second since Minato can summon Gamma the boss to fight susaano won't be that big of a help for itachi , looking at both speed theres no way itachi can catch up , chakra wise, Minato has a lot of chakra seeing he can sumon gammabunta while itachi from his illness , has a lot less , he won't be able to hold long with susanno since he's sick and Minato can still get with a rasengan . THE END
BTW I'm not a Minato Fan , I'm a Naruto fan
BTW I'm not a Minato Fan , I'm a Naruto fan