I can't honestly see them reshooting a massive chunk of the movie based on reviews of a teaser, this close to the films release. Whether we like the new designs or not they are what we are gonna get, playmates have made the toys and there's no doubt a ton of other merchandise with there new look on.
Plus hardly any transformers fans were happy with how bays first film was shaping up before the film released, yet bay did not change it.
It would have been great to get turtles that look how they always have, without the lips, noses and overly busy bodies (I mean Mikey with the necklace seems to have a plunging neckline) and I hoped bay would give us something like what I grew up with such as the still amazing Jim Henson turtles. But this is bay.