@MrTerrorist: what james0246 intended to say was that
Spoiler:
the camouflage pathogen chosen at the end of the movie is not a definitive solution to the crisis - if anything, it only gives humanity a temporary reprieve. There is a possibility that this measure will
only be effective for a short amount of time, before the virus evolves
again and causes the infected to become smarter...and disregard the symptoms of terminal illness exhibited by the fleeing refugees and incoming troops.
There is therefore a chance that in the sequel (since it's supposed to be a trilogy) the camouflage pathogen will have become useless and a new globe-trotting race for a cure/countermeasure is required.
According to this Yahoo! article, the original ending for the movie involved a battle in downtown Moscow, fought by thousands of civilians forcefully conscripted by the Russian army and armed with lobotomizers (the end of the theatrical version shows glimpses of this scrapped scene)...so maybe we'll get to see that in WWZ2.