Re posting to get your answers….
Ahh, Im sorry Alex, I meant on answering yours…
@alexwolf:
Luffy doesn't need a plan to fight Shanks. When he wants to do it, the only thing he must know is the whereabouts of Shanks, and this is all. Then he will just go there, walk in Shanks's place and challenge him, after having a big party.
Very true, Luffy doesn't need an alliance to take on Shanks. But you said it yourself, Luffy needs the location of Shanks. If Law has that information, then I'm sure Luffy would be more than happy to team up with Law.
Again Luffy doesn't need a plan, and thus the alliance would be pointless if it was done for Shanks. As i said before Luffy doesn't need any help to go and fight Shanks, so why would he make an alliance for it?
As we can see, Luffy has grown to like Law. As we all know, he likes to ask anyone he finds interesting to join his crew, Law would almost certainly fit this bill. However, since Luffy knows that Law is a captain, he's not about to ask Law to join, but to ally with Law would be like him joining the crew anyway, so it's no skin off Luffy's nose.
This is very open as of now, so anything is possible, but still, the point stands. Luffy would want to fight Shanks one on one, with no help or information. So Luffy wouldn't want to take part in defeating someone as close to him as Shanks with a strategic plan and a key information. It is too cunning, thoughtful and even disrespectful for someone as Luffy, when it comes to battling a friend.
I may have stated my position on this before, but my point is that Luffy doesn't sweat the details, just as long as the end result gets him to see Shanks. It's possible that whatever Law has planned flew right over his head when and if Law mentioned Shanks.
"Here is an interesting guy that I'm is indebted to that may have info on Shanks, let's team up!"
but as you said, it is all up to Oda where this goes.
Shanks is someone very important to Luffy and i don't think that he would challenge him, when someone as irrelevant to Luffy as Law presents the opportunity. I think that Luffy will battle Shanks, when he wants to, or when he is near him, or even when he randomly sees him, and surely without any kind of help, no matter how little (why would you need any help to openly challenge an old friend to a battle is beyond me).
Like I stated up above, Luffy just needs the location of Shanks. If Law knows this, Luffy would jump at this info, just to see his old friend and rival. Whatever Law has in store, Luffy just needs to know he's gonna see Shanks again and that's enough. If Law presents a problem to him, he knows his crew will help in taking Law.
Of 'course Luffy's reaction should be taken into account, but as said by many others before, the possible reasons for Nami's and Luffy's reaction are too many for us to make an accurate decision based on them. Also while it is true that Oda likes to surprise his fans, when he does it, the surprise fits with the story and with his character's personalities, where challenging Shanks wouldn't fit with Luffy's character.
Luffy wants to surpass Shanks. To someone as simple minded as Luffy, a knock down, drag out fight is what the doctor ordered.
The point Im making is that we shouldn't just drop the idea that Shanks is a candidate and there are some points in the story that point to it…especially this scene:
he is very interested in the hat…take from that what you will...