These storyboards were not used for the final film. These storyboards were included on Metrodome's Ultimate Edition DVD.

Autobots Vs. Devastator

Just after Megatron says the line mentioned above, Devastator is shown ripping open a door. This seems to be where these storyboards start, as Devastator enters the city. He doesn't get very far in though as Ultra Magnus appears with Tracks, Sideswipe and Red Alert.

The Autobots all transform and do what any Autobot would against such a large foe: blast it with missiles. Devastator is broken apart, but...

...the Constructicons are all still alive and open fire on their attackers, who are forced to run off deeper into the city.

Sadly Red Alert doesn't make it and gets shot in the back, and is presumably killed. As the Constructicons charge in, Megatron looks through the hole in the wall which Devastator created.

Of all the rumored deleted scenes to this movie, I think this one may have been animated. When Megatron says let the slaughter begin" Devastator is shown ripping open a door, just like in the first storyboard above. A little later, Megatron can be seen standing in front of the hole in the wall Devastator made, which is featured in another storyboard. He's smiling, which makes sense as he's presumably just seen the Constructicons storm their way in and kill Red Alert. There is a storyboard for this also. When Optimus Prime turns up moments later, the hole in the wall behind Megatron can be clearly seen just before he leaps at Prime.

Trailbreaker's death

When the Decepticons run back to Astrotrain, this storyboard points out a "DEAD AUTOBOT", who happens to be Trailbreaker. Trailbreaker's death is not featured in the final film.