Check out what the sales looked like in 2003 (when the dates are the same, ie Christmas day on a Thursday)
http://vgchartz.com/hwcomps.php?cons1=GC®1=All&cons2=PS2®2=All&cons3=XB®3=All&start=37899&end=37990
So they should fall next week, but not significantly, so if Wii ends this week with 1850-1900k, it will likely have 1600-1700k next week.