Board Thread:Naruto Gaiden/@comment-32622248-20170719100834/@comment-31405103-20170729200652

Thekillman wrote: Bambusek wrote: Well, it looked like no one (beside Bijuus), not even Uchiha "know-it-all" Madara, knew. Well, as far as people knew, removing the Biju killed the jinchuriki. As far as the Konoha experts knew, the Uzumaki could extend that time. But actually testing if a reseal could save them would put them at massive risk. Mito never lost Kurama, and Kushina was the second Kurama jinchuriki, leaving no room or opportunity to try. And as far as we know, no other village possessed people like the Uzumaki, meaning that few were probably aware that one could survive the extraction at all.

Very true, the only reason Kushina and Naruto didn't die straight away was because they were Uzumaki. If Minato had sealed even a small fraction of Kurama's chakra back into Kushina she would've lived.