Of course it could lead to something new! Nobody is debating that. The point is that people point to the equivalent result for the electron as evidence that th

Of course it could lead to something new! Nobody is debating that. The point is that people point to the equivalent result for the electron as evidence that the existing theory is correct, when it gets only one correct out of the three leptons. There is no guarantee that the "new" thing will be another step along the same path as the existing theory. I very strongly suspect that we'll need to backtrack a bit, perhaps a lot, and then walk along another parallel path to get to that new thing. It might look very similar, but the subtle differences can make all the difference in allowing forward progress.