Treyarch always said they were going 4 map packs and there has always been high demand for the W@W maps for those who did not get hardened or prestige edition.

Also the map packs names are and easter egg aswell

First Strike
Escalation
Annihilation
Rezurection

A.k.a FEAR

Well i think its stupid that these developers stop making map packs because another CoD came out, i would've carried on buying Mw2 map packs despite Blops coming out!