Do not read if you have not read the last chapter(618)
This theory is simply that the hokages may break out of edo tensei, like madara and then useing minatos ftg, could arrive at the war. Then to help balance the power levels, sasuke and taka might join madara. Hashi would fight madara, minato would fight obito, hiruzen and tobirama would fight sasuke and taka and naruto and the alliance would fight the juubi.
Simply though, the hokages would join the battle field, after breaking free from edo tensei.
Simply though, the hokages would join the battle field, after breaking free from edo tensei.