Sanji doesn't need that, just like Luffy. He fights whoever comes into his way and is among the strongest.
Thats one of the best things about Oda's writing, we can't tell what is stored for Sanji's future and so far things look very promising given Oda's hints. He is writing Sanji carefully.
And i don't see why Shanks is here, Luffy is already a Younko, he doesn't aims to surpass Shanks or something, this isn't like Zoro and Mihawk.
Although Luffy and Sanji are Warriors of Liberation and Science, that could tell us something, possibly.
But one thing is for sure: Oda always had great plans for Sanji.
Thats one of the best things about Oda's writing, we can't tell what is stored for Sanji's future and so far things look very promising given Oda's hints. He is writing Sanji carefully.
And i don't see why Shanks is here, Luffy is already a Younko, he doesn't aims to surpass Shanks or something, this isn't like Zoro and Mihawk.
Although Luffy and Sanji are Warriors of Liberation and Science, that could tell us something, possibly.
But one thing is for sure: Oda always had great plans for Sanji.