Women aren't going to be interested. Maybe they can beef up a love story (Shia and the chick) but then the hard core fans will be pissed. Most people who grew up with Transformers might not be all that fired up about a movie and young kids have no idea what Transformers are. Add in the fact that Michael Bay almost has a negative box office value now and you have the making of a bomb.
Add in the fact that this is an absolutely loaded summer and the film could fall through the cracks. Live Free or Die Hard opens the week before, Harry Potter opens the week after. It needs to have a HUGE opening because it will likely drop at least 50% after and then face more and more comp as the summer rolls on.