Are people not considering a chakra cloak of some kind?
I'd expect someone to have already mentioned this, but doesn't the outline of the mystery man in question resemble that of a chakra cloak? Whenever Naruto uses his chakra cloak, it looks quite similar to this outline:
Now I'm not saying with certainty how someone else may have gotten a chakra cloak, but think about this for a second. If someone had some sort of foreign chakra emanating around them, wouldn't it change how people sense them? I'm one of the people that think the guy near Sasuke could still be Kabuto, simply because the circumstances surrounding Kabuto, if in fact he is free from Izanami, are yet unknown.
Kabuto may have spliced more foreign DNA into himself. Kabuto also could have been experimenting with yet un-discussed research. Perhaps he's even obtained a chakra cloak of some kind. The point I'm making here is that it is far too early to rule out Kabuto as a candidate because we know nothing about the current state he is in post-Izanami.
And the fact that the person in question seems to have a chakra cloak around them.....well it begs the question if Kabuto was able to incorporate that into his experiments somehow. It could also be a cloak similar to the aura the elder son emanated, but I consider someone like that entering the story at this point to be laughable to say the least, but Kabuto creating some variation of it may be possible.
Thoughts, comments, suggestions, concerns?