The other project in development was a movie based on the Beast Wars part of Transformers, lore, with a script being written by James Vanderbilt, who previously wrote Zodiac as well as the currently filming Scream 5.
The new movie is apparently set in the same universe as Bumblebee, the most recent Transformers film, though it’s unclear if the movie is a direct sequel to that or not.
Bumblebee is notable as the movie was much more warmly embraced by critics that than most of the Michael Bay franchise was, though, it did not perform nearly as well at the box office as those films did.