User blog comment:Dinosel/One Piece Discussion/Theory! Shanks' Arm!/@comment-25926617-20160716201616

I think that Shanks, like whitebeard, never really wanted to be pirate king or anything. He is similar to Luffy in the way that they just want to have fun and be free. So Shanks losing his arm wasn't too big a deal for him. HIs only goal is to keep his friends safe. So while it may not have been intentional it was more like a sacrifice. Shanks would have died for Luffy in that moment if he had had to. Obviously a sea king is nothing to him so he didn't but it has always seemed weird to me that he lost his arm in that situation. Which gives your theory a little more water.

I do believe that Shanks always thought that Luffy was gonna be stronger than him one day and say Roger in him though which again does support your theory. We will probs never know if you are right tho