Katy has come too hard and too fast. I honestly didn't think her airplay would grow to what it is right now this soon so I thought BL would get at least 14 weeks, but now along with the massive sales, she'll really coming for it.
Regardless, Blurred Lines is not done breaking records. It will most likely break Gotye's 6 million finish if it keeps posting 200K+ weekly numbers for the whole month.