Deadline is reporting that the early results are in from the Transformers Writers room and the powers that be have decided that Akiva Goldsman will write the script for Transformers 5 while the Ant-Man writing team will take on an animated feature. The Transformers 5 script is being written on the assumption that Mark Wahlberg will star as Michael Bay as director but neither are actually signed up for TF5. As Bay tweeted, "Re: directing TF5. No, it's not official. I have not committed to any idea as of yet. Just met with Steven [Spielberg] and we are discussing." Previous interviews with Mark Walhberg indicated his interest in a sequel is highly dependent on Bay's involvement so if Bay returns, Mark returns. No Bay and Paramount is going to have to work harder to get Walhberg to return. Likely they are hoping that Akiva's script might be enough to get Bay to sign up again.
As for the animated movie, writers Andrew Barrer and Gabriel Ferrari is described as "an origin story that focuses on Cybertron". Its unclear if they literally mean how the planet and its inhabitants came to be or really mean the origin of the Great War and the events that ignite the civil war between the Autobots and Decepticons. The former seems a bit odd (but doable) while the latter seems more likely considering the War has been referenced in every film in some form but no real explanation provided for it. I just hope they take inspiration from the IDW writers who have done an excellent job back filling that period, especially with the relationship between Megatron and Optimus Prime. Not saying they should copy it, but try to make it more complicated than simple good guys want freedom vs bad guys that want to rule the world that was essentially the reason for the war before IDW took a wack at it.
As for a time frame, Akiva has little time has he needs to get something on the page by year end so pre-production can begin in time for a June 2016 principle photography start date. As for the animated movie, those take at least two to three years to complete so those writers have more breathing room. I suspect Paramount is hoping that the writer's room ideas and franchise Bible they put together will allow them to move away from waiting on Michael Bay to recharge his batteries between movies and go back to an every other year pattern for the core movies so they can release TF5 in 2017, the animated movie in 2018, and TF6 in 2019. In short, Paramount saw Disney's Star Wars plan of a movie a year and said "we can do that with Transformers" and these script assignments are the first step.