Orochimaru will always be a sinister character that people love to hate. Simple fact. He's aiding the alliance because he has no choice right now. He could have turned over a new leaf, but chances are he's just calmed down some but still keeps his ambitions of learning all jutsu.
Obito as of now will be the final villain (Or so it seems) unless the Juubi takes on a conscious human-like form. Obito is playing with emotions that should not only hurt Kakashi, but him too. He's proving to Kakashi that he will never return to the way he once was, and that his entire life is directed towards the eternal genjutsu.
Obito will arrive on the battlefield probably after or during Madara and Hashirama have a rematch. Kakashi will be defeated and nearly dead, and Obito will face off against the rest of the Kage and alliance. And yes, with his Kamui hax back at full power, he can do this.
Madara really seems like he doesn't care about the Moon's eye plan. . He's probably going to be gone soon. I personally think that he will defeat Hashirama in a 1 vs 1 and finally surpass his rival. His goal his whole life. With that, he will feel some deeper emotion and slowly fade away. Like Sasori did. It's obvious that Obito isn't giving up his life for Madara, so he really won't get to be the Jinchurrikki.
And unless is somehow on deaths door soon, and decides to use the Rinne Tensei to bring Madara back real quick. . .Just for a quick middle finger to the alliance, he most likely won't be the Juubi's host or a final villain.
And don't forget about other amazing villains we've had in this series.
Pein was by far one of the most evil and cold hearted characters here. Kakuzu was a greedy man who cared so little for his comrades that he killed them when they annoyed him. Deidara was an insane bomber who simply liked to watch things and people explode. Gaara, when he was insane, was an awesome villain.
Sasuke when he was evil was alright, we all sort of liked him in some way. And who didn't love Itachi when he was still known to be only evil? I find it hard to believe anyone didn't like him back then. Sasori is iffy, he got his redemption and refused to kill his precious Grandmother it seemed. . He wasn't all that bad.
And Kabuto was a great villain, both playing with peoples emotions and revealing his own. . His sad commitment to following Orochimaru's ways, and learning the Edo Tensei Jutsu. . . He's underestimated as a villain. I rarely hear him mentioned.
All in all, the ones you mentioned aren't THAT bad currently. And you're sort of missing the bulk of the villains just for the recent ones. The villains are good in this series, that's the truth. And do not worry about the war, the Juubi itself is more powerful than any of the Edo Kage. That barrier won't hold for long.
