Notes

Hiruzen sealed Tobi and and Hashi in seconds. Minato was purposefully delaying RDS. If you complete RDS you die instantly. So he held it off to talk to Naruto, to set up the sealing of Kurama into him too and putting his own chakra and Kushina's into the seal. He couldn't wait with RDS because Kushina was getting weak, so he performed RDS first to suppress Kurama with it. Against Orochimaru it was clear that being sealed suppresses all your abilities so once hit by RDS, being able to perform Izanagi is impossible.

and that the target can't see RDS. Only if they happen to know the signs could they use Izanagi in time. Even then, RDS can be channeled through shadow clones, so not even the long-range version is needed. If the soul's already been eaten then it would be too late to activate it. If Izanagi had been activated any time before that, then the user should be safe. If the technique has finished and the Shinigami has eaten their soul, then they're dead. If the Shinigami was in the process of dragging the Izanagi user's soul out, then theoretically they still have a chance.

Questions |

I'm assuming that the five tails won't be taken away as well seeing as it's an entirely different entity? Or will it due to being sealed inside her?