I wouldn't put any money on anything being significantly different in terms of tone or construction in the next Transformers film. The takings for Age of Extinction confirm that they still have a solid recipe. Why would you change that?
I'm torn on this. I mean its basically a good thing, Bay was never going to deliver the sort of movie most fans would like to see. Even those who like the Bay films (such as myself) would still like to see a different type of film at some point I imagine.
In a perfect world some one more in line with the fandom comes in with the same level of creative control as Bay and makes a masterpiece.
The problem is that what ever your view of Bays work, I think most can agree that he is 100% committed to making his vision, however dumb that vision and it shows on screen. Even if it is just in the form of ever increasing explosions and product placement.
For comparison watch TMNT, Bay exec produces and there is some of his visual style on show, but it's just a bit flat/pedestrian/dull/generic. GiJoe 1 and 2 I would say are the same (and Battleship to round out the Hasbro properties) they feel made by committee.
With the movies so successful I doubt the powers will want to rock the boat meaning a random guys gets put in the directors chair and told to make something like the last one, but will be hen pecked to death over the course of production and by the time we walk out of TF5 we'll all be missing the Bay films because at least they had a bit of visual flair to them.
The one positive is that the way TF4 ended theres room to make a really different film if some ones willing to take a chance.
This time he's actually got a project to work on instead. Some true-ish story thing abou Bhengazi.
"I used to think it was a terrible thing that life was so unfair. Then I thought, 'what if life were fair, and all of the terrible things that happen to us came because we really deserved them?' Now I take great comfort in the general unfairness and hostility of the universe." — Marcus Cole, Babylon 5 — A Late Delivery from Avalon