After WW sales come out Halo 4 will be at about 6.45m sold and there's still 3 weeks of sales left! 7.4m seems inevitable now
My prediction threads:
Wii U will sell under 40m units (made on 14th September 2012)
PS Vita will sell under 20m units (made on 30th September 2012)
Wii U will sell under 7m in 2013 - I was right