How does one follow up a box office success as big as the first live-action Transformers movie? For Michael Bay, the answer was "By directing four more Transformers movies." The director has sometimes expressed reluctance to return to the franchise, though, perhaps hoping to move on to smaller, more arthouse-type films in which lots of things explode real good.
Bay first publicly quit the director's chair after after Transformers: Dark of the Moon, a movie he felt compelled to make to right the wrongs of the "mess" that was Transformers 2. He then changed his mind and returned to direct Transformers: Age of Extinction, perhaps feeling that the series' course correction was not yet complete - but once again declared that after that, he was done.
Now Transformers 5 is on the horizon, and readers who excel at pattern recognition will not be surprised to learn that Bay will be directing it. However, in an interview with Collider promoting 13 Hours, Bay once again said the movie would be his last for the series. When the interviewer pointed out that Bay had said as much before, Bay reiterated his claim:
"Yeah, I know, right? But it's like, that's all they want to do is franchises. That's all they want to do. I had to beg to get to make [13 Hours]."
When the interviewer tried to bring the subject back around to what was in store for future Transformers movies, Bay wasn't having it. After mocking the reporter's dogged persistence in extracting any potential morsels about the series that he could, Bay concluded with, "I can't tease s--t." Clearly even if Bay isn't done with the Transformers movies, he is at the least done with answering questions about them when he's trying to promote something else.
With Transformers movies planned until at least the year 2025, the series will go on with or without Bay. No doubt there is also a lot of pressure on him to continue his stewardship of the movies as long as they continue to rake in bundles upon bundles of cash, but based on this interview it does not seem like he wants to do so forever. The timing seems right for the studio to bring in someone else with a new (or, rather, somewhat different) vision for how giant robots should explode - but Bay is stuck with the monster he created until at least 2017.
Transformers 5 is tentatively scheduled for a Summer 2017 theatrical release.