Some people are predicting way too low for LT. If an FPS sells 800k first week, it will probably sell over 4 million LT. Look at CoD4 on PS3. 450k first week, 4 million LTD and selling.
EDIT: Lifetime. I think around 6x first week sales is a good amount, so 5-6 million.
Call of Duty has become an exception, it has by far the best "legs" of any other PS3 or 360 game, in fact better than many Wii games.
KZ2 will certainly be more frontloaded.... but, the lower it's first week sales, the comparatively better legs it will show, so it's not as simple as multiplying the first week by a certain number.
It is a likely candidate for roughly 3-5 times the first week making up the lifetime total.... I would guess if it sells around 800k to 1 million on the first week, it should be heading for about 3.5-4 million sales.