Board Thread:Naruto Discussions/@comment-26773508-20150905054531/@comment-26773508-20150905073941

Legendary Super Saiya-Jin 4 wrote: Kurama stated himself that if his other half is sealed into Naruto, Naruto will survive. Kushina and Minato had no way of knowing that unless Kurama told them, which he didn't. So Kushina assumed she would die if Kurama was resealed back into her. But considering the fact that jinchuriki sealing jutsus are known almost universally throughout the Shinobi nations, and also the fact that these jutsus seem to have ancient origins (Hagoromo used it), it stands to reason that people would have eventually found out that resealing the bijuu to the dying jinchurikis, immediately after it has been extracted, would prevent the jinchuriki from dying. The condition being that the jinchuriki needs to be alive for a short time after bijuu extraction, and within that time period the resealing should take place. Now most jinchurikis would not survive even a few seconds after the extraction. However, the Uzumaki were known to have such powers. Moreover, they were the greatest experts on Fuinjutsus (or Sealing jutsus). Given the fact that the Uzumaki clan has existed for hundreds of years, and the fact that they were experts in Sealing jutsus, it seems implausible that they didn't know Uzumaki jinchurikis, at least, could be saved from death through resealing.

Hence, Kushina not knowing about the resealing thing sounds a bit implausible. It's a minor weak point in the plot, but not a plot hole IMO. But it's still a weak point.