What will make or break Kinect - and Move - is word of mouth. All marketing is great, but just look at Dante's Inferno, Superbowl commercial, big primetime commercials, etc the game sucked and the word of mouth was poor, GOW3 didn't have as big of a marketing and it outsold both versions combined.
The Wii also sold hugeloads on word of mouth, people saw how fun it was, told their friends, their friends played with them and wanted to buy one for themselves, just think back to 2007 or so how much everyone of your friends were talking about the Wii.
Word of mouth is the best and cheapest marketing tool, if Kinect - or Move - is fun and it works, it'll do extremely well. Actually it'll do well regardless as both peripherals are getting bundles, and I'll be surprised if there's a "Core" PS3 or 360 without Move or Kinect.