This fight didn't start everything, it merely perpetuated it into the modern ninja world. As we know it was the So6P's decision to make his younger son his successor and the following fight between the older and younger son of the So6P's that started everything. Madara and Hashirama were just another notch in the timeline as Sasuke and Naruto could be, or they could break it, depending on the choices they make, especially as Naruto is "the destined child."
Granted, for the Naruto and Shippuuden series, Madara and Hashirama were still just a part of the ninja system, which is what started their actions, so even then they didn't start it all. It goes back too far to pin it on one person or pair, unless you go back far enough, as the further the feud propagated the harder it must've become to end it. Especially when such powerful individuals were born into those bloodlines, ensuring it's continuance.
Still, I'm certain we'll see that fight. I really hope that Kishi leaves no holes, and covers his bases when he shows it, probably multiple times. What I'm not sure about though is who besides Madara will we see it from, perhaps the Kyuubi and/or a remaining Edo Tensei, Zetsu,...? As well, as how reliable will the version/s we get from whoever tells them be? I expect it'll be like the recount of the Kyuubi attack 16 years ago, and need two or more sources in order to get an accurate account of what actually happened. Madara can't be trusted to tell you your own name, let alone the events of that day without authentication.
Peace
