Just curious, what other threats to Earth in pre-existing fiction are there left? We've already gone through the MacGuffin that can transform Earth's machines, Solar Harvester, transporting Cybertron to Earth, and Cyberforming. What's left?
Well there is still dark energon, unicron, quintessons (Or the creators) and the bay team could always make something up. Hell why not have the major threat be SKYBITE!
Overlord, Decepticon Justice Division, Zarak, etc... I could see them going headmaster or targetmaster route since Joshua and Cade are both inventors and are wanting to work with the Autobots again (so it seemed at the end of the movie)
I'd like for them to go after our "other" natural resources and leave these macguffins alone for at least one movie
What would Cosmic Rust do to humans? Actual rust gives us tetanus, but Cosmic Rust doesn't seem to have that effect on humans.
Nothing, who said the beings who are using the cosmic rust are after mankind? Earth is basically the transformers's home now. However staying to the chemical warfare idea, what was that stuff called in G1 that turned all the autobots/Decepticons/humans into angry red monsters? (The Return of Optimus Prime)
