Imo, TF4 should play out on another planet 20 to 30 years in the future from DOTM's timeline. Not on Earth. This would be a colony planet which happens to share a handful of similarities to Earth and it's now housing a totally new cast of Autobots & humans. I think this new planet scenario will be a chance for totally new & creative ways of character interaction & development, since we're not bound to the restriction of Earth's physics and laws anymore. Who's for another planet scenario too ?