"Transformers: Age of Extinction" earned nearly $1.1 billion worldwide and there is no doubt that Paramount Pictures is now moving forward with a sequel.
Sources at Air Herald cited that the new films are getting into darker territories, with "Age of Extinction" functioning as a soft reboot to introduce the new tone, new characters, and plot direction of the franchise. The last film ended with Optimus Prime heading into space to meet the Creators while the other Autobots remained on Earth to protect Cade Yeager's family. For this reason, many speculate that the next film would be set in Cybertron.
However, producer Lorenzo de Bonaventura denied these plot rumors, and stated that the next film would still be set on Earth and that it would have a very similar dark tone to "Age of Extinction." This rules out any major event in space and it could also mean Optimus Prime might not make an appearance.
However, Peter Cullen, voice actor for Optimus Prime, has stated that he is not so optimistic about the change in tone. At the SacAnime 2015 conference, Cullen expressed his desire for the franchise to return to its fun-centric roots.
The upcoming film is still in pre-production and it has been speculated that it will be pushed back to 2017 from its originally-planned summer 2016 release, especially now with rumors spreading around that director Michael Bay may not be returning to helm the project.
According to the same sources, Jonathan Liebesman, the director of last year's "Teenage Mutant Ninja Turtles," would be helming the new film if Bay is determined to leave the franchise behind. Liebesman has not yet confirmed or denied his involvement in "Transformers 5."
There is one important player confirmed to return though. At an MTV interview, actor Mark Wahlberg already confirmed he will be coming back to portray Cade Yeager. Rumors are also spinning about either Megan Fox or Shia LeBeouf making a comeback.