Nearly forgot this part. Madara isn't relying on anyone to be on his side in the 4th ninja war. He's relying on their own petty jealousys and paranoia's tearing them apart. The only one's we know will stick together are leaf and sand beacause of the ties between Naruto and the Kazekage. Pretty much everyone else will turn on leaf quickly because of the crap Danzou pulled, and I'm sure the others all have their little differences we don't know about due to the story focusing on the leaf shinobi. Madara is counting on these differences coming to a head now that nothing is holding them back. He's going to feed on the ensuing chaos to allow him to obtain what he desires. If the world is at war, it will be much easier for him to go for the Bijuu. Lives splattering through arterial spray all over the forest makes you notice Naruto a little less.