The leaks were pretty conclusive regardless of when they were released, primarily because of the videos that leaked which would have been near impossible to fake, as well as Nintendo issuing a copyright claim on the videos within a number of hours basically confirming that they were real. I'd say people's reactions would have been the same, mainly the response to Duck Hunt.
Speaking of leaks, I've been wondering about the Gematsu leak now that the ESRB leaks have been confirmed. How is that they managed to predict some characters without turning out to be true? I mean, they predicted MegaMan and Wii Fit Trainer before the game was even announced. I highly doubt they would have randomly guessed Wii Fit Trainer completely by chance and actually been correct.