The WSJ cover page with Loki+Luffy+Zoro makes me think he will indeed be the final big fight of the arc, despite him being a clear misunderstood tsundere, since all the other arc villains got similar color pages.
However if Oda is going to try to paint Loki as a schemer who's gonna betray everyone next chapter he's already fumbled the portrayal. If he was a real trickster who wanted to deceive people into freeing him, he should've accept the Gimmick Knights' deal and turned on them shortly after, or in front of the M3+Giant Pirates he should've just immediately passed out to convince everyone he wasn't a threat instead of putting them all on edge with that dumb attack on the tree.
However if Oda is going to try to paint Loki as a schemer who's gonna betray everyone next chapter he's already fumbled the portrayal. If he was a real trickster who wanted to deceive people into freeing him, he should've accept the Gimmick Knights' deal and turned on them shortly after, or in front of the M3+Giant Pirates he should've just immediately passed out to convince everyone he wasn't a threat instead of putting them all on edge with that dumb attack on the tree.