As we know at the end of Season 2.5 or the Starscream Returns Arc Optimus stated that he never actually went back to Cybertron and is in fact says that he has been working with some Old Friends. With the first half of the Combine Force season taking place on Earth dealing with the Stunticons and whatever Soundwave is up too. Then maybe the later half focusing on what is happening on Cybertron involving the rumored Cyclonus. I've been thinking quite a lot about who some of those "Old Friends" could be. Of course I know Team Prime of Course. Addition I'd include are Ironhide, Jazz, Brawn, Prowl, and Kup, throwing it out as the season is called Combiner Force I was hoping for the appearance of my personal favorite Armada Jetfire. Combining with Optimus in RID 2015 would be so cool. But that's just me.