I think the last phase of Shikaku's Plan to defeat the Juubi is for Kakashi (with Kurama chakra-cloak) to Kamui the Juubi, or at least part of it in order to incapacitate it.
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Remember how in chapter 617 Kakashi was saying that the Naruto-Kyuubi's modified chakra cloak he has now is far more powerful than the kyuubi-chakra he received prior to the Juubi's revival
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Then on the next panels Kakashi said that prior to receiving the first kyuubi-chakra he couldn't move large objects or use Kamui in succession
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Based on Kakashi's statements, the initial kyuubi-chakra he received made his normal Kamui 3x more powerful, which enabled him to Kamui large objects or creatures like Hachibi.
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But this Naruto-Kurama modified chakra cloak Kakashi had received is even more powerful as Kakashi stated:
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Based on Kakashi and Shikaku's conversation regarding Kamui and Kurama's chakra, I think the final phase of their plan to stop the Juubi is this:
Kakashi with Kurama-chakra cloak will Kamui the Juubi to incapacitate it
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Though it is unsure if Kakashi even with Kurama's chakra cloak would be able to Kamui the whole of Juubi, I think they plan to Kamui a specific part of Juubi's body:
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The Juubi's Head
It's called a decapitation strike Kakashi tried to decapitate the Gedo Mazo before:
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This time, with the Kurama-empowered chakra cloak, Kakashi will Kamui the real thing: Living Juubi's Head:
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Naruto and the Shinobi Alliance might provide distraction so that Obito wouldn't be able to counter Kakashi's Kamui like the last time he did with the Mazo.
Like they did here:
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If Naruto and others are attacking Obito and Kakashi Kamui'ing the Juubi's head at the same time, Obito would be in a serious dilemma, will he phase out with his Kamui or will he counter Kakashi's Kamui, but if he does counter it with Kamui, then he will need to materialize a part of his body making him vulnerable to attacks
Not to mention that Obito and Madara have begun to lose control of the Juubi, so they have their hands full at the moment.
I have ascertained that Shikaku's plan was to Kamui the Juubi's head, based on this panel in 613:
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The moment when Shikaku said that "were just like flies buzzing around its' head." he immediately contacted Kakashi, and in the page after the panel above, the Juubi's head was shown:
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So in conclusion: The final phase of Shikaku's Plan is for Kakashi with the modified Kurama empowered cloak will try to Kamui the Juubi (particularly its' head) in order to incapacitate it so they can deal with Obito and Madara once and for all. Naruto and the others might try to distract Obito so he wouldn't be able to counter Kakashi's Kamui this time
I am not proposing if they are going to be successful or not, what I am proposing is this is what Shikaku had in mind all this time.
