I can see them outselling both XB1 and PS4, but combined sales of both XB1/PS4, i don't believe that.
If Switch is selling more than 2M that several insiders are all but confirming is happening. Then NSW will indeed outsell them both combined.
What part arent you believing? That NSW is over 2M or that PS4 and Xbox are naturally selling less than they did last year with no deals from PS4 and lesser momentum for Xbox compared to last years December?