@Shin: Presumably the tiers will act in the same way as COD's perks: basic one has a certain effect, and higher tiers extend or improve that effect in various ways.
Underlined part was my point No insider info there, i honestly have no idea on the actual answer.

As for "modules will be unlocked depending on your play style, what modes you mainly use, etc", that sounds very similar to the COD method, whereby completing "challenges" using the basic perks will unlock the pro version...in other words, I agree with Talon.
Yeah, point is that you're not going to be rewarded with things that you're not going to use. As someone exampled, a camper is not going to make any use an ability that is melee/close quarters. It would of course be quite silly to implement a reward system that didn't operate based on your utilisation of the system in the first place