An early promo poster at the Licensing Expo on in America this week, for the Bumblebee movie... so, nothing revealing, as it just has a big Bumblebee head and the release month.
It includes a "Transformers Universe" logo on it though, which could be a temporary thing for this promo poster, or something Hasbro will be featuring on their future Transformers movies (because when you start including numbers beyond 4 or 5 it makes the concept look tired and old... most sequels do worse than the first movie, and more so with later sequels).
Besides, focusing on the titles rather than the numbers makes it easier to remember the different movies, especially when you have the next few so close to each other... you need investors and retailers to distinguish between them when they are currently dealing with things that are a year or two away.