Here is my prediction for chapter 501.
Chapter 501: The Departed
Minato: W-who are you?!
Madara: You have no time to be asking questions. I'm not going to say it again - step away from the host, or your son dies.
Minato: Isn't there something-
Kushina: Just listen to him, Minato! You know there's nothing else we can do.
Minato: But Kushina...
Kushina: It's over for me, Minato. But it doesn't have to be so for Naruto; he has a life ahead of him - how can I take that away from him?
Minato (tearing up): All right...masked man, you will bring Naruto to me, and once he is in my arms, then... [cannot finish sentence]
Madara: Just as I expected.
Madara takes his arm away from Naruto's face, and begins walking towards Kushina.
Madara: Move away from her, and you will get your son back.
Minato: I'm sorry, Kushina.
For a reply, Kushina cries out in pain, testament of the fact that the Nine-Tails is dangerously close to being released from its host.
Minato begins to move, but the next second he appears behind Madara, and tries to stab him, but nothing happens.
Madara: Trying to kill me?
Minato (in thought): I went right through him...how is that even possible?!
Madara: Your son's death might teach all you Konoha ninja not to be so arrogant.
Minato: No!
Madara: But not this time. I'll spare his life, but I assure you, we will meet again. And when that time comes, he will not be granted the same mercy.
Minato tries to attack Madara again, but this time Madara places a hand on Minato's shoulder.
Madara: It is like unwritten law that a Hokage sacrifices himself for the village, is it not? Now it's your turn.
Along with Naruto, Minato is sent to an unspecified location.
Madara: Let's begin.
Kushina: What have you done to them?!
Madara: Minato will die soon enough. As for Naruto, he will become an important piece of the puzzle in my plans, and I intend to utilize him to the greatest ability.
Kushina: Leave him out of this! He has no part in it; he's just a baby!
Madara: He has everything to do with this. He will become a ninja that will exceed all others, for I can already see a burning ambition in this child that will take him far in life; but eventually he will have to face the destiny that will inevitably rise up to meet him.
Kushina: You won't get your hands on him that easily!
Madara: Perhaps not, but I have ways of making things work. Just like what's going to take place right now.
Madara enters Kushina's mind, and stands directly in front of the Nine-Tailed Fox; his Sharingan becomes visible.
Nine-Tails: Damn you! Just when I thought you were dead, you stand before me with those detestable eyes! You and that Uchiha clan, I'll rip you all to pieces!
Madara: You are going to be gaining your freedom tonight. Therefore I suggest you obey my command.
Nine-Tails: I submit to no one! Especially your filthy kind!
Madara: It's not your decision.
Kushina, clearly in agony, makes a helpless plea for assistance, but of course no one comes. A few minutes later, the Nine-Tails is completely released, and is wreaking havoc on the land.
Madara: We're going to be heading for Konoha.
The Nine-Tails, chained by the Sharingan, changes direction that it is now heading for Konohakagure.
Madara (in thought): Interesting...while I extracted the beast from her, a part of her chakra and mind still remain. But it is no matter; as long as I have control of the fox, my plans will be going exactly like I want them to.
Meanwhile, Minato finds himself back in his office. A terrible nausea sweeps over him, as he frantically looks around. He finds Naruto lying beside him on the desk, completely quiet. Then he remembers the masked man who confronted them. Minato then hears a roar, and knows it is that of the Nine-Tailed Fox. He realizes Kushina is dead. A lone tear runs down his face, but he knows he must perform his duty. Quickly grabbing Naruto in his arms, he runs outside the Hokage Tower, but notices there is no one in the village. Everyone has gone to fight the fox.
Minato: Why didn't anyone alert me the fox was coming?
On the battlefield...
Ninja: We have to stand our ground until the Fourth gets here!
Madara (in thought): The Fourth will be coming soon...Sarutobi will be unable to make the sacrifice, because he has his own problems to deal with now. Everything is going as I planned.
Fifteen minutes later, Minato, Naruto and his summon Gamabunta appear across the fox. Everyone cheers at the Fourth's arrival.
Minato: Fortunately, it hasn't reached the village yet. I'll be able to stop it in time.
Gamabunta: What are you planning to do, kid?
Minato: Nothing. There's only one thing I can do. Gamabunta, do you notice the way the fox is moving? As if it's being forced to do this, against its free will?
Gamabunta: Now that you mention it, its behavior does seem a little odd. Are you saying that someone is controlling the fox?
Minato: Exactly. The Nine-Tails suddenly appearing just doesn't make sense to me, unless someone is controlling it.
Gamabunta: I don't know about that one, kid. Who's controlling it, then?
Minato remains silent for a while.
Gamabunta: Did you hear me, kid?
Minato: I'm just thinking about what I'm going to do now. I'm going to seal the fox into Naruto, otherwise the village will be destroyed.
Gamabunta: Well, it's not like I can stop you. Do what you have to do, kid.
Minato: Please keep him safe, Gamabunta. Due to me being unable to tell anyone else, please try to have the villagers respect my final wish: Naruto is a hero, and defeated the Nine-Tails. If it weren't for him, the fox would have destroyed the village.
Gamabunta: All right, kid.
Minato: If you can, please get me as close to him as you can.
Gamabunta leaps in the air and lands directly in front of the fox.
Nine-Tails: A toad? I'll enjoy clawing your flesh out. And who's this here? Konoha's pathetic Hokage. There won't be another one after this.
Madara: By sealing the Nine-Tails, he thinks he will defeat the beast, but he has presented an even greater threat by sealing it into a Konoha ninja - his son, no less.
Minato: Shiki Fuujin!
Nine-Tails: What are you doing?! Death upon your village, and all those wretched ninja who control me! I am the Nine-Tailed Fox!!
Minato (on the cusp of death): I'm sorry, Kushina, Naruto...I hope...you know...that I love you...more than anything... [dies]
Madara: It is done.
The silence then was as loud as crashing thunder. Soon, all the Konoha ninja cheer at the defeat of the fox, but once fall silent as Gamabunta approaches.
Gamabunta: The Fourth Hokage is dead. But there was one last thing he wanted to tell you all...
A fair distance away, a figure emerges from the ground, next to Madara. It is Zetsu.
Zetsu: How did it go?
Madara: Exactly like I planned. With the Fourth of the way, the village is drastically weakened, and they will need to put the blame on somebody for what just happened.
Zetsu: The Uchiha, right?
Madara: Precisely. The seed of suspicion will soon be planted, and when it is, anger will germinate as well. Despite having to lose the fox, we are to going to gain much more. And eventually we will get it back.
Zetsu: Nagato only has partial control of the statue...
Madara: He will master it. But that is in the future. Now we must focus on what lies ahead: the destruction of the Uchiha clan.
My prediction is most likely too long for a seventeen-page chapter, but I just wanted to share this with everyone. Hope you enjoy.