Since we saw The Fallen (the originator of the Decepticons) in ROTF I think it would be great to see Alpha Trion in TF3. Even if it is just a small role. If you don't remember Alpha Trion he is one of the oldest living Transformers according to G1 lore. Not only did he rebuild Orion Pax into Optimus Prime he was Primes mentor and guide (just as The Fallen was with Megatron).