Remember Devil May Cry 4 shipping 2m in it's first week?
SCIV on X360 is doing pretty well globally. It's the 5th most played title on MGC this week, and was at #4. VERY few games ever get to that spot, and any that do become million sellers. The last game that wasn't one of the major titles (H3, CoD4, GTAIV, GOW, RB) was Battlefield: Bad Company, which has sold 700,000 units in 5 weeks.
I think US sales will show us that SCIV has sold around 200,000-250,000 copies between both platforms.
That would put SCIV at 400,000-450,000 sold through. I wonder how Scamco got retailers to pre-order 2m copies...