If less than 30 million GPU's have been shipped in by the end of 2014, then it's probably fair to say less than 29.5 million consoles have been shipped, as there would have to be 300-400k currently in consoles under production and not yet shipped. Even if Sony's numbers were a lie and it was 18.5million shipped (not sold), the xb1 would still be slightly overtracked because there is no evidence of shortages, which means given the sales of the holidays there must be at least 500k in the supply chain. Therefore, even absolutely best case the XB1 can't be more than 10.5 million, which would put it half a mil overtracked.
Far more likely is that the ps4 has actually shipped 19 - 19.5 million, and therefore the XB1 is overtracked 1-1.5 million.