A source close to the production of Transformers 4 has cleared up some elements about the film. While the term 're-imagining' was thrown around, the fourth film will be a straight up sequel to the last movie. It just won't be told through Witwicky's point of view. As to whose point of view it will be told through, that's unclear right now, but it's also unclear which - if any - human characters will be back.All of this is pure speculation. I doubt studio and Bay are even past the spitballing stage, tossing out random ideas while in meetings to discuss his two picture deal. I doubt any real movement on story will occur until after a writer is hired.
"Michael realized it needs to be more like the last hour [of Dark of the Moon]," this source told me. So expect lots of big action, lots of carnage, lots of military badasses, very few silly bits.
Really except for no Sam (since Shia LaBeouf says he is done), this is the same approach used for Dark of the Moon. Even as critics bashed the film, they often complemented the last hour of the film, The idea that Bay would take the parts that worked and extend them is pretty much the same formula he attempted (even if not always successfully) with the previous films.
As for the "hybrid" reboot story, even though Lorenzo di Bonventura used that term, he also said it was more about taking a story plot point and going in a new direction with it allowing for completely new characters to be used in the same universe.
The closest recent anology that I can think of for what I believe he means is Final Destination 5. (Spoiler) At the end of the film you learned that it was really a prequel to the very first Final Destination film. You had new characters, same over all themes and formula that tied directly into the series but was still its own seperate thing.
There is nothing stopping the next film from taking place with some other Transformers team on a NEST mission against an alien incursion (who says it always has to be Decepticons). The three films "real time" was a period of around 5 years where the Autobots evolved into essentially their own agency in the US government. This presents a lot of time, lot of missions, and world of story possiblities. All without having to use a single character from the first three films while still keeping it tied into those films.
That is even assuming Bay just doesn't jump the story ahead a few years with a new big bad. Transfandom wants Unicron but I just don't see it happening. I am thinking more along the linese of Jhiaxus. For the last nearly 30 years, Transformers has re-invented itself about every five years while staying true to its roots. No reason the movies can't do the same thing.