I take back a little on what I said though, Shanks doesn't want
confirmedly to discover the treasure, but I find that likely, a strong possibility.
Firstly, we have Shanks saying he wants to access the final island his own way, getting there in his own pace with his own crew:
That shows he shared a good deal of interest in reaching the island, as he wanted to venture there when he had the strength to do that his own way. That also denotes a good level of curiosity.
Eiichiro Oda said in one of his interviews that Shanks is the character that resembles him the most and the own Oda stated that he sees why many fans are itching in curiosity for the one piece, meaning logically that the matter would also be of interest to Shanks, being someone that resembles him a lot.
When Roger was executed, we can see Shanks holding his hat and getting his hands to his chest, a gesture that most take to mean someone will carry the other's will:
Rayleigh also said Shanks is one of the few to take away something Roger said:
I think this means that Shanks put on himself the mission and burden of becoming the pirate king and shaking the world. Whitebeard said that the world will be "turned upside down" when the treasure is found. The finding of the treasure is directly tied to the "carrying of Roger's will" as apparent in White Beard's last words.
Roger passing the hat to Shanks also might be a gesture of trusting him to carry on the will of the D and to really change the world.
Luffy also seeing Shanks as a role model ought to mean something as well. Luffy was set-on becoming the pirate king right after his encounter with Shanks, his role model:
Oda's words:
"Luffy wanted to be exactly like Shanks in the future. Shanks is established by the author himself to be Luffy’s role model, not just a figure he respects, like Rayleigh, Ace or Roger."
Btw, that's my input. I admit it isn't 100% sure but I think it's well backed up that Shanks was the prime candidate, character-wise, to become the pirate king until Luffy got into the scene.