I'm one of the people I think you are refering to.... I'm no hoping anything, I wish Xbox One the best sales they can get. My prediction is based on information i get through internet.
If Xbox One sold 150k in UK from the 1 million total (more or less) announced by Microsoft, I assumed that the number of total Europe and Others might be around 350-400k, so....1 million minus 350-400k is something around 600-650 for North America.
Of course i might be wrong, but that's the risk to try to figure out sales numbers....