Michael Bay was hesitant about doing TF in the beginning, because to be honest most Hollywood directors do not consider adapting a cartoon-based franchise as a worthwhile and respectful endeavour. Given how most of the other live-action cartoons have been received over the years (The Flintstones, Speed Racer, The Smurfs, etc), this shouldn't be surprising. MBay had to, let us say, give the franchise adulthood He turned it into a hardcore sci-fi war story, with polarizing reactions among the fanbase and normal viewers (which I won't go into). He's staying on as producer, but we don't know what kind of directors will appear, and like I said above it would be difficult to hire respected directors to work on a live-action cartoon adaptation because of how Hollywood considers such properties. I'm hoping I'm wrong though. Times have changed, directors are now seriously trying out live-action adaptations of cartoons (notably Disney with their Renaissance films). And so I hope this franchise will attract some legitimately good directors, not just okay ones like Jonathan Liebesman (who I hear may do TF5) but notable and respected names. I'd love to see people like James Gunn, Kenneth Branagh and the Wachowski Bros hired to work on a TF film someday.