I just want to point out some early dialogue from Shanks that people have very obviously overlooked:
He agrees with Buggy that being a pirate is doing things your own way and fighting to the finish on clashing ideals.
This scene is exactly what I've honestly based my Shanks theories on as a foundation Clearly Luffy wants to fight Shanks. Clearly Shanks does too based on how he looks at his bounties.
Let's say that Shanks wants Luffy to accomplish something because of this DF and he assumes Luffy has a particular role in doing so, what if Luffy disagrees with the method? What if they clash on any idea in the future, considering they are in fact meant to clash? If taking Shanks' words seriously here, a clash of ideals could mean a fight to the death. This is why I think this is where the series will reserve its climax on.
Shanks, imo, is Oda's biggest and oldest plot twist. If he's meant to be this "inspirational" figure that ends up being not who he says he is, then I think we might be gearing up for a VERY emotional finish to this series. Luffy being inspired then subsequently betrayed by someone he trusted is actually a great plot twist and one we seem to be heading towards