User blog comment:The ASL Pirates/Will Someone other than Luffy Fight the Strongest Opponent?/@comment-24.235.56.170-20150621182338

With the prevalence of haki in the New World, the only fighters that even could take the main antagonist are Zoro and Sanji. At least until the others learn/master it anyway.

Or if they go to some pissant little island. If Luffy was bored enough by a "strongest opponent" that was a weakling, someone else might step in.