Sadly, this new TMNT film is going to go exactly the way the Transformers Films did under Michael Bay's involvement; Director or Producer? it doesn't matter.

What we're going to get is a film about Casey Jones & April O'Neil's burgeoning & blossoming love for one another with a recurring cameo by the Teenage ALIEN(!?!) Ninja Turtles - Sadly it'll probably makes hundreds of millions of dollars at the Box Office & be considered successful & yet 2 of the longest lasting Boys Toys franchises will still be without proper movie adaptations.
(Of course, we will always have the 80s Turtle Movies though )

Megan Fox's involvement? - I don't think this will do her or anyone else any favours.
(Someone/something to look at though )