It's just wishful thinking. The person who made that theory is just searching for things to back his theory up and as a result is interpreting things in his favour.
Danzo is dead and that's 99% sure, that 1% is just because you can never be sure till the manga is finished.
1: Why would Danzo fake his own death? To escape from Madara and Sasuke? Very unlikely but still possible, however why is he faking his own death for everyone else too? This is a humongous plothole in his theory. It makes absolutely no sense whatsoever. Where is he now then? On vacation? On top of that why would Kishi have given him a flashback about him and Hiruzen, a fitting last panel before his death, to let him eventually survive then? Makes no sense. That person makes an analogy with Kisame, however when Kisame "died" the first time he just shmirked. When Kisame died for real then he too was given a flashback as a last panel and then died.
2: He makes a complete incorrect analysis of Shisui's powers. Shisui's powers are very "popular" with the ninja's, Danzo rated it higher than Izanagi, however the maker is just assuming a lot of things that are not proven nor are there even hints that it could be like that. He says that Danzo didn't try it, well it was clearly stated that he needed it for Madara, if he actually would have been able to cast it on multiple persons, he would have done it instantly. But you can't do something you just can't do, especially not because it was already stated that it's not a jutsu that can be used often nor very long. Danzo didn't expect of Sasuke to pierce Karin, so there was no reason for to already to use Shisui's eye completely "as a last resort". On top of that Madara was far away from Danzo. How the hell are you going to place a Sharingan master, along side two other people, under a genjutsu while he's standing so far away.
3: His issues are also useless and utter BS. Yamato has also the Shodai's cell's, but he can't start using Zetsu clones now can he. Also Yamato has way better control over his powers than Danzo, so how would Danzo be able to use it? Not to mention that Zetsu can copy people's chakra by absorbing it and then make a special clone out of it. When would Danzo have done that while Madara was continously watching along side Sasuke, also a Sharingan master and Karin who's a master sensor. It's not possible, on top of that he should also have placed that sealing jutsu on the clone. His arguments are not cohesive. Because he has the shodai's cells he must be able to use that trick? That's nothing more than a gamble, especially because Danzo doesn't have much power of the Shodai's cells.
4: Erase his existence of life? Once again that's BS as why is he trying to make him appear death towards the entire world, even his subordinates? On top of that a genjutsu can't remove the seals, whether you see them or not they're still there and they're still active. It's nearly impossible that no one noticed that, also how is it possible, Shusui's eyes or not, to affect countless of people who are miles away with a genjutsu o_o that's just bull, that's what Madara is trying to do and for that he needs the Juubi =/
Danzo is dead, that entire theory makes no sense, is full of plotholes, gambles and wrong assumptions. The reason as why Shusui's eyes are so powerful is because it fools the person mind, which is different from a normal genjutsu, which fools the sense. However as a result you need to continously change the way it is used as for instance to fool Karin's mind you need to make it so that her sensoring skills would not notice it, while for Sasuke and Madara it would require a differetn approach. This is beyond Danzo's skill, if Danzo was able to do that, he would have tried it instantly and he wouldn't need to fake his own death. That's the largest contradiction in that entire theory. He's saying Danzo faked his own death because he tried to use Shusui's eye so hard and then apparantly failed, so his theory is then that he succeeded, but if that eye was so strong, why would he fake his own death while he could kill Madara and Sasuke?
This theory is bull, it contradicts itself.
