To be fair, E3 2006 gave a pretty good picture of what the three consoles would be (in the case of the 360, it was already out). Every analyst had the chance to revise his predictions at this point, but nobody really did.
That's the thing though, with the GC and N64 doing only well enough to ensure that there definitely was enough demand for another console, it would have been a gamble to argue otherwise for the Wii. It's like an upset win during the footy. Bookies will always stick purely to statistics, past matchup history, comparing team sheets etc and of course there's a degree of popularity, which in Nintendo's instance was usually ascribed to their handheld market and not so much their consoles post SNES. There are always arbitrary variables that can never be predicted. In this instance it was the consumer.
That isn't to say the man is always right, Pachter says some really stupid shit sometimes.