Clearly Michael Bay has decided that if you can’t write a coherent plot you just need to cram the movie full of more stuff so audiences can’t tell. In the first Transformers: The Last Knight trailer alone we got the Arthurian Legend, Unicron, Bad Optimus Prime, and a dragon that is probably Nemesis Prime. I mean you spend thirty minutes with each of those plot lines and you get a two hour movie. Will it make any sense? No.
I can only hope that much like Transformers: Age of Extinction that none of the plot lines truly intersect. Like the Robodragon from the Author timeline is a totally different dragon from the one they have to fight in the future, and that the Unicron killing sword has nothing to do with Excalibur. Then when we are all scratching our heads trying to figure out what just happened, we will get Rodimus Prime because why else would Hot Rod be in this movie. Plus he can put a bow on everything to get us ‘excited’ for Transformers 6.