I AGREE. at that time tsunade risks more damage to protect her village than nowShe was able to summon full size Katsuyu even with her lower half detached. I also don't think she'll be healing the Kages to their healthiest, and it seems as if Katsuyu will be the one doing most of Tsunade's regeneration.
I don't think she's going to sacrifice herself. Compared to when she protected the villagers of Konoha, healing the Kages is probably simpler to accomplish.