I think it's a narrow win for Straw Hats, since Shamrock is basically the big bad boss that Luffy will inevitably have to get stronger in order to defeat
We've seen in the last chapter that he's not even staying on Elbaph anymore. I still think they will call him back if the God's Knights have to fight the Straw Hats, but that's just a theory.
But I doubt he'll be fighting the whole yonko crew. There are currently three other knights, and more will likely come when Mary Geoise finds out the Straw Hats are there. While I don't believe another Elder will be involved yet, I do believe they will dispatch a sizeable force when they do find out. Shamrock will very likely come back and be the obligatory stronger-by-a-hair-than-Luffy vilain.