Its been discussed several times already. Kabuto can't summon just any person he wants just because they're dead. All the other Edo tensei's were summoned because not only did Kabuto have they're DNA, but not one of they're souls passed on when they died, so they were still bounded here. Sakumo's soul was also bounded but passed on after he spoke to Kakashi when Kakashi died. Even if Kabuto had his DNA, it couldn't work.
I highly disagree. You really think that all of Kabuto's summons were applicable with IWR because they were stuck in limbo? If anything, the fact that Kakashi helped his dad move on makes him applicable with IWR. Clearly, Kakashi's dad was in limbo when they talked, he had not yet fully passed on. His dad saying "Now I can finally see your mother" proves it. After being set free, he moved on to where all other people do, the afterlife. Please don't say that this is your reason the White Fang cannot be summoned. I think it is very clear that he is indeed a candidate for the jutsu.
i think kabuto is about done summoning his dead soldiers. the only one left is the elusive 6th coffin. besides that i think its done.
As for this, It is very clear to me that one Edo Tensei, besides the 6th coffin, is unidentified.
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See that guy on the far left as part of the Dan/ Asuma/ Neji's dad group? We never found out who that guy was. Parts of his body were shown many times before, most notably here:
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I mean it clearly is a Konaha shinobi considering the group he's traveling with. Therefore, the White Fang is a perfect candidate.