At least that's what Brian Goldner (president of Hasbro) said. Here's the whole thing:
Hmm, I wonder if they'll keep any of the previous characters. Maybe they're going the 86 movie way with Rodimus, Galvatron etc. I wouldn't mind. It would be interesting to see but very difficult to create because they have to start from scratch.Transformers 3 didnít meet expectations. What about Transformers 4?
Brian says TF3 did well in boxoffice. Regarding toy sales... itís because of same characters in all three movies. This is why Transformers 4 will have a new cast of [robot] characters and it will be a story revolving around these new characters. Brian said Transformers will branch out to more categories. For example; during Transformers 3, they had an idea to expand the Transformers brand on Little Kids segment. This was the origin of Rescuebots said Mr. Goldner. Soon the idea took a separate life and evolved to a separate toyline. He said itís normal for any brand to experience the situation (what happened to Transformers 3 toyline) and stated that brands need re-imagining, reinvent and hinted that the same is to happen with Transformers 4.