As I mentioned in the sales comments section:
KZ2 is tracking almost identical to COD: WAW (PS3 version.)
KZ2
Week 1: 718k
Week 2: 320k
COD: WAW
Week 1: 735k
Week 2: 322k
I don't think it will be able to hold up as well in the coming weeks, given that we aren't entering a holiday period, but I think it's safe to say at this point that KZ2 should reach 2-2.5 million handily enough.