TFW have posted up scans from a new Empire Magazine issue that features the Transformers Cinematic Universe, giving us some details about the 5th and 6th (Bumblebee) movies.

The article is over four pages, and has Michael Bay doing a lot of commentary on the current project, and how the next one is coming along.

TF5 is noted as being a combination of two of the 14 story ideas to come from the writers room - Merlin and King Arthur, WW2, and the story arc already being set up in TF4 (which would probably be the Quintesson element).

The Bumblebee movie is said to be set in the 1980s, while another two projects are in their early stages - and animated prequel based on Cybertron, and maybe one set in ancient Rome... but it's still just in discussion phase.

Shia certainly left an impact on Bay, as he is mentioned quite a few times in the article... even to the point of having to change the direction of the movies when he left, almost like a soft reboot (you sort of get that feeling when you see TF4, like it is the first chapter of a new story that borrows a couple of elements from an existing movie).
If it wasn't for Shia leaving, apparently there wouldn't have been a need for a writers room to generate the future direction of the franchise.

And it seems, that the dog of his that was named after the 2007 character Bonecrusher, recently died. This pet of his was known by fans back during the first movie, because of who Michael Bay named him after.