Shanks is more important than Kaido and Linlin for Luffy. Luffy specifically said, Shanks won't be the first Yonko that he defeats.
Shanks said he won't see Luffy because of their promise.
Shanks makes mihawk his girl in terms of importance and power to the story. Shanks is rival with Kaido, the strongest pirate in the world, and the main character gave his word to the guy, thus he won't see Shanks until Luffy defeats a Yonko and becomes Yonko level.
Shanks already proved himself against the strongest pirate in the world; Kaido. Shanks is >>>>>>> mihawk who is equal to Vista.