In my honest opinion, hashirama alone could beat him. I also believe edo bm minato can solo him now. Along with edo tobirama, but he has them to face. Kyubi chakra cloaked shinobi army, naruto, sasuke, all the kage and ALL of the tailed beasts. I mean, how could he possibly win?
Madara will use rinne birth to bring back everyone killed in the war. Its required for plot. Whats a shinobi world without shinobi? There would be no point anymore and everyone mine as well just die. So in order for the plot to make sense its required.