I don't think Luffy is actually going to change his approach to anything. Oda wants Luffy to appear as though he's working through a flaw to justify his upcoming power growth. If that growth happens without being anchored to a genuine low point, it won't feel earned. It'll just feel like a trick.
Luffy is Luffy. Authors don't tend to change aspirational heroes. I wouldn't expect anything more than a moment where Luffy verbalizes some kind of "growth" or change in mentality, if even that, but ultimately, it won't amount to anything fundamentally new. He's been through these ruts before and always came out the other side victorious by simply being himself.
Gaban isn't telling Luffy, "Don't turn into a Genie, son" because Oda is never going to stop drawing whatever he want's. That's all that was. It wasn't a failure on Luffy's part, it was Oda having fun. All Gaban is telling Luffy is to do better. It's a broad statement, "just be better". But if you believe that Luffy's version of "better" is going to look like some fundamental change in his personality or approach, then no. That's not what I expect.