So as far as I know the identity of the blue motorcycle has not yet been revealed. I'm wondering if it could be a character based on Armada Sideways. I know the name was used for the toy in RotF but I don't think it was actually used in the film. Regardless, in Armada I thought Sideways was a very cool character. Revealed to be part of Unicron. A kind of emissary. If they have a bigger plan for the Transformers films going forward he would be a great way to plant the seeds of Unicron coming down the line.