A lot of people have always speculated that this character is Bonnie, or in other words, they are different variations of Bonnie. But that isn't true, as stated in Kriya Studios' response on an email.

They specifically state that Bonnie is a purplish-blue animatronic rabbit. While the "rabbit heads" in the TRTF trailer are either gray, dark blue, or etc. They specifically point out that just because it looks similar to Bonnie, doesn't mean it's Bonnie.

In other words, I believe that these animatronics are nothing more but the Spiraled Animatronics. The Spiraled Animatronics were described in "The Return to Freddy's: Chapter One" as animatronic robots that look similar to their predecessors, "Freddy," "Bonnie," and "Chica." However, due to copyright reasons and what not, Tyler had to make sure that he didn't want to brand anything with an animatronic bear, so he scrapped Freddy.

Then leading on to scrapping Chica, because she would also look way too identical to Scott Cawthon's design.

But with an animatronic rabbit, you have a bigger variety of designs you can think of for a rabbit. You have the mascot of Duracell Batteries (a pink rabbit), you have Blue Bunny (the blue rabbit mascot for an ice cream brand). Blue Bunny isn't Bonnie, and yet he's a blue rabbit.

In conclusion, the Bonnie heads isn't Bonnie. They are the Spiraled Animatronics shifting into the dead husks that is a deer skull, signifying that they have uncloaked and revealed the true enemy of TRTF: Chapter One, the Cosmic Wendigo!

Let me know what you guys think of the theory in the comments! If you agree or disagree with what I've said on the post, let me know your feedback and thoughts!!