Transformers 5 rumors never seem to be in shortage these days - from crossover theories to casting gossip. This week, we'll be looking at the top rumors that have graced the overactive entertainment rumor mill.

Possible GI Joe Crossover

A film crossover has long been rumored, ever since G.J. Joe and Transformers producer Lorenzo di Bonaventura hinted at such a possibility with Cinemablend back in 2013.

This theory is not without basis considering that the G.I. Joe and Transformers toy-line is owned by the same company, Hasbro. Also, both franchises have had crossovers in a number of comic books. The film adaptations for G.J. Joe and Transformers were produced by the same production company, Paramount Studios.

With the successful Marvel's Avengers and Agents of SHIELD crossover, a similar treatment for G.I. Joe and Transformers is possible. But for now, there is no official confirmation whether moviegoers are destined to see the All-American-Heroes star alongside the Autobots.

Mark Wahlberg Returning, Megan Fox Casting Uncertain

Mark Wahlberg, who starred in the previous Age of Extinction installment, may be returning in Transformers 5. Last year, the Inquistr reported that Wahlberg may not be coming back to the franchise. However, the actor told MTV that he was committed to doing more Transformer films in December 2014.

Meanwhile, rumors of Megan Fox's return never seem to die. Fox was booted from the franchise in the third Transformer installment after on-set tensions with franchise director Michael Bay. Since then the two have seemingly reconciled with Megan Fox starring in the more recent Teen Mutant Ninja Turtle film adaptation. Still, this alone does not confirm anything. With no recent word from Megan Fox regarding Transformers, it seems ever more unlikely fans will be seeing her return to the series.

Release Date May Not Be in 2016

Though Transformers 5 is likely, there are no official announcements as for yet. Last year, ScreenRant published an article about possible 2016 Paramount projects that included Transformers 5 and Star Trek 3. In 2015, the same publication later confirmed that the studio is not actively planning a sequel to Transformers: Age of Extinction.

Avid Transformers fans may note that there was a three-year gap between Dark of the Moon and Age of Extinction. Theoretically, this means a 2016 release date is very unlikely.

Even so, future Transformer films are in the works as evidenced by the recent hiring of "I am Legends" writer Akiva Goldsman, who will oversee the scriptwriting process. Hence, it is possible to see other Transformers installment and spin-offs in the distant future.