First week sales are NEVER a good indicator of long-term success. There's always the risk that it'll be a fluke.
To begin with, Smash and Mario Kart will be far better indicators of the WiiU's prospects. If those can't sustain the WiiU's sales in a big way, along with all the other stuff out for it by then, the system will be dead and buried as far as I'm concerned. I'm not expecting much of a lasting impact out of Pikmin.
Have some time to kill? Read my shitty games blog. http://www.pixlbit.com/blogs/586/gigantor21
:D