Dead End already exists in the movie continuity thanks to the Scout (or TF1 Movie Jolt if you accept the retcon). Having said that, not being able to use the Dead End name won't necessarily stop him from putting Stunticons in the movie - after all, only four of the seven movie Constructicons have their G1 counterparts' names (Mixmaster, Long Haul, Scrapper and Scavenger). I would be surprised if we had another Decepticon gestalt in the third movie though consider we already had Devastator in ROTF, and with the Constructicons being an army like the Targetmaster Seacons in Masterforce, I don't see the need for them to have another gestalt. An Autobot gestalt would be possible - but I personally hope they just go for something new. We've seen a gestalt (and a combiner!) in the movie - kay thanks Mr Bay, something new please.