I think Tsunade would die against Obito, not Kurama. She would defeat the fox and then attack Obito who is already a high difficulty to beat
Minato would defeat Pein, not an easy victory but he has speed on him and tons of moves.
i dont see tsunade defeating kurama on her own, not in a hundred years
Minato gets tossed around by Pain and more people die than the original scenario, and less people die in the first scenario b/c Tsunade would be saving and healing the village's inhabitants via Katsuyu instead of fighting Obito, and Hiruzen eventually uses Shiki Fūjin on the Kyūbi, meaning Obito's plan is still foiled.
Lol
People need to understand that the village getting destroyed is insignificant if you manage to save as many people as you can.
i dont think more people would die, given the fact tsunade was the one who provoked pain to use shinra tensei, she started a rampage of words with pain and made him mad thus making pain destroying the leaf, had minato been in her place, he wouldnt have tried scolding pain and would have gotten right into battle avoiding the big almighty push which destroyed the leaf.
Besides tsunade wouldnt have lasted a minute against obito, the only reason why obito didnt go after hiruzen who was the one taking care of kurama was because he was engaged in battle with minato, but if we swicht to tsunade she gets defeated neg diff and then obito hunts down hiruzen leaving the leaf helpless