Yeah its pretty clear Tsunade knew what she was doing when she gave him a necklace with her grandfathers chakra in it when we know what it was that made him Hogake.
I want them to let us know more about what Sakura said about Kyubi healing naruto slower than before. Maybe kyubi used too much power when he used the 4 tails so he coulndt heal naruto as quickly as before. Yamato did say "this is what jiraya..." Maybe the healing being slower is something that happens as he used more tails. Maybe kyubi is a little like 8 gates. Tail 9 uses so much chakra that no healing can save naruto.