There are things in the CG trailer that the game simply won't surpass. Like the explosions for example. The explosions in the CG trailer were so freaking sweet that if they could nail those down, it would be freaking cool, however I have my doubts if that is even possible at this point.
The CG trailer while amazing looking it really isn't anything that the PS3 can't do or surpass. As you can see, the animations in the real-time trailer already surpass the one shown in the CG trailer.
The final version of Killzone 2 WILL surpass the CG trailer, i promise you that