I don't think I would say Infinite Jest has three plots, it feels like it does because the plot never happens, we get the setup and then it is dropped right when it actually starts. We can view it as three plots but those plots don't provide anything useful towards understanding. They would be more accurately viewed as triangles, they are containers for information.
Edit: I also don't think we can fully interpret Infinite Jest through the Sierpinski structure, that was the structure of the first draft which was something like 500 pages longer and had the bulk of the novel in the end notes. It has been too long since I last read it to say what the structure of the final form of the novel is but I think he may have just made the gasket more linear; he keeps repeating the full triangle but each time he goes a bit deeper with the iterations.