This prediction blows John.
Once Nintendo sorts it out (ie stops giving American supply to Europe due to the poor Dollar) They will be doing what they usually do, which is giving almost half of their production to the Americas.
2.4/2 = 1.2 million.
Edit: although now I re-read I notice you said U.S. so I am doubtful we will see regular sales above 1 million by NPD until Nintendo increases production some more, because Europe is an increasing market to Americas will likely ge 45% or less of shipments, which we then have to cut down to mean USA only, so at the rate of production Nintendo is aiming for at the moment USA will probably only get 900k per month.
Until the last quarter I don't think we will see NPD over 1 million on ANY 4 week month, and it is unlikely for the 5 week months.
I think we will have to wait till 2009 before this comes true John, unless you are counting November-December as regular