Shanks is probably the Yonko that has the least endgame goals of all the Yonko. Shanks seems to be that person that is just having fun and partying with the people he likes and loves, while still desiring to be free and lawless.
Recently Shanks made his appearance during the Reverie Arc. In chapter 907 we saw Shanks at Mary Geoise meeting with the Five Elders while in chapter 908 we saw Im-sama in the Room of Flowers and a silhouette of a suspiciously placed sword that looked exactly like Shanks’ sword. I’m not saying it’s actually his sword but it could be a possible foreshadow.
Oda said in an SBS interview that Shanks’ sword was named Gryphon. Throughout myth Gryphon’s are known for guarding treasure and priceless possessions.
This has led to speculate that one possible endgame goal for Shanks might be that he is ‘guarding’ Raftel and the ‘One Piece’ until a suitable successor of Roger comes into play.
What if perhaps he is guarding a treasure but the National Treasure of Mary Geoise instead of the One Piece?
*Theory by Syskill