I think that if Minato didn't use reaper death seal he would have survived also if he didn't transport kurama outside of the village because that took alot of his chakra
I have a better one for you. Remember when Minato hit Tobi with that Rasengan, and then caught him with that seal to release the Nine tails from his control?
Right here:
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Instead of stabbing him in the stomach, he cuold've stabbed him in that little eye hole and destroyed his sharingan, stabbed him in the heart and killed him, or even sliced his head clean off his shoulders.
....but he decides to stab him in the stomach. Plot no jutsu is a baby-carrying dog