After lots of madness and mayhem, Steppenwolf ends up with Harry claiming that he would try out the Magic Theater again someday and do a better job. He declares that someday he "would learn how to laugh", because Pablo and Mozart, figures that led him through the Magic Theater, were showed him the correlation between laughing and being a freakin' genius.
The text wraps up pretty nicely this way, because we have the idea that Harry has finally learned the lesson about his endless options rather than being stuck in wolf-man mode. It also tells us that Hermine is still alive, and so is Harry, because he has another chance—it was all an illusion. Phew. We like Hermine.
And that really is the lesson of the whole novel—there is always another chance because our existence is actually infinite. We have to see things from the perspective of the immortals so that we can keep trying out new things all the time then going back and trying out a different road. It's like a choose-your-own-adventure novel in real life!