Way to beat a dead horse.... At any rate, here is my take that I made a couple of weeks back;
I realize this has been speculated on, and there are too many threads about this already. The vast majority believe the gift Minato has for his son is the rest of Kyuubi chakra. It seems like people here absolutely refuse to so much as consider any other possibility. Like they are flat out refusing to think any further than they already have. I'm not looking to change anybody's mind, or to tell anybody that they are wrong. I don't know that, and neither does anybody else on this forum. Keep that in mind when speculating. We are not Kishi moto.
Here's the problem I have with the "chakra gift theory"; We know that Madara and/or Obi to want the Kurama's chakra. That's the entire point of starting this war. Madara is exceptionally intelligent, and well informed. He knows that he will need all of the chakra, and will try his best to get it. So, Kurama's chairs showing up this way seems unlogical to me. I'm certain Naruto will get the chakra, but not this way. After everything is said and done, and the bad guys are dead, he'll have all of it. He doesn't need his dad to hand it to him on a silver platter.
The look we see on Minato's face when he realizes that he gets to fight by his son's side is one of pure joy, and excitement. For obvious reasons. The way his face lit up when learning that he has the chance to see his son shows how much pride he has for him. How strong his faith in him is. He never planned to die a few hours after his son's birth. He believed his life was truly starting. Wife, son, and title of Hokage. When Obito attacked, we saw how far the man was willing to go to protect what's his. As he is dying, he remarks on his remorse for burdening his infant son with the demon's chakra. He knew exactly how difficult life would be. If it wasn't for the sake of protecting his village, he never would have done what he did. He then stated his faith in his infant son. He knew that Naruto would overcome, and that he wouldn't give up on his dream. He has never doubted that for a second. Since he didn't want to put the half of the chakra that he did into his son, why would he now that to give him the rest? Yes, it is argued that it would be for a weapon, and more power. Minato has great faith in his fellow Kage. He doesn't doubt them, or their abilities. He should believe that all of them entering the fight is more than a simple power up.
I'm thinking that the gift is something tangible. A symbol and reminder of who Naruto is, and who his parents were. A way to validate and express his deep pride and faith. He never thought he'd get that opportunity, and he's absolutely thrilled that he does now. What could serve that purpose? Well, what is Minato known for? Being a hero, who gave his life up at a very young age to uphold the duty of Hokage. His trenchcoat has become a symbol, almost. No other Kage wore anything like that. It was his own thing. His style. I believe the gift is Naruto's own trenchcoat. He hoped that his son would follow in his footsteps, and had it made for the day he could pass off the baton of Hokage to his son. Again, symbolizing the strength of his faith. He died, and probably believed he wouldn't be able to do it. Now he has the chance, and he is absolutely thrilled. It would serve as a power up, in a sense. After realizing how proud his parents are, he will get the moral boost he needs to carry on. If he has any doubt at all that he will succeed, this gift would squash that, and reinvigorate his will.
Lastly, bringing the Kyuubi chakra straight to the the battlefield would be tantamount to handing it over to Madara, almost as a favor. Knowing that all of the Kage valued one thing above everything else, putting that in direct danger doesn't seem feesible. They would rather die, or even have their own loved ones die, than to hand over something to the enemy that would absolutely end the village. They aren't stupid people. Especially Hiruzen, Minato, and Hashirama. They must know how stupid it would be to wave it in front of Madara's face like that.
