I'm a big fan of the Transformers. As a kid, I watched the original series, and revisited it when my younger brother first got into Robots in Disguise and Armada. I watched all of Michael Bay's explosion-fest theatrical takes on the franchise, and thoroughly enjoyed the War for Cybertron game. After the announcement that Grimlock would be joining the cast in Fall of Cybertron, I did a bit of deeper digging and discovered that Wheeljack and Sunstreaker would also be joining the Autobot's fight against the Decepticons. While Optimus receiving a bit of a makeover for the sequel was mildly amusing, I was more interested in who else might be climbing aboard for the sequel.
What follows is entirely speculation - they are my own thoughts/wishes on who might be in the new game, and have not yet been confirmed by High Moon Studios.
- Trypticon: I don't think we've seen the last of Mr. giant robo-dinosaur. He survived a fall from space to Cyberton. I'm pretty sure he could just as easily survive a fall into the lower levels of the planet.
- Constructicons: With Grimlock on the Autobot side, it only seems logical that High Moon Studios would balance this with something similar and classic for the Decepticons. I don't know that we will necessarily see any other Dinobots, but the Constructicons seem plausible. Assuming this sequel is longer than its predecessor, a few more boss fights would add to the epic scale and fan-oriented nature of the game. And I can think of no better giant green-and-purple robot to face down than Devastator.
- Shockwave: His appearance as a DLC multiplayer character in the first game led me to believe that me might have been intended as a cast member, but ultimately left on the cutting room floor. I don't know how they could go about the sequel without incorporating Shockwave in some way or another, considering how much of a tribute the games are to the old cartoons.
- Arcee: Another multiplayer character from War for Cybertron, Arcee could add some variety to the scout-class characters. Whereas Bumblebee was the excited young trooper and Sideswipe was sort of the cool kid on the block in Jazz's absence, Arcee could act as a more careful and reasoning balance to the boys. Adding Chromia and Elita-1 in as her squadmates for a mission or two could lead to some interesting and creative tactics with the scout-class abilities and weapons.
- Jazz: He was a DLC character. He was a scout. Same stuff that I said before, just as they apply to Jazz.
- Ironhide: He made a brief appearance in the first game, portrayed as an war-hardened bot. It was a cool balance between G1 Ironhide and his live-action movie counterpart, and I think High Moon can more greatly explore the history he and Optimus share.
There's a taste of what I think could end up being in the final product. As for the rest of the cast from War for Cybertron, I think most of them will be returning, though there may be a few exceptions with some of the less-prominent characters (like Warpath and Barricade). As new information is revealed, I may revisit this list to make additions.