Back from the dead is a hard card to play and very few film series have pulled it off successfully. The Matrix series got blasted for it's poor use of back from the dead and Transformers kind of burned up all it's back from the dead cards when you had Megatron, Prime, and Sam all back from the dead in the same film. The undead are about the only way to pull off cool back from the dead but I'm not sure about zombie Megatron or sparkly Starscream.
That is a good question because it needs to be something cool instead of something that is going to come off as corny. I kind of hope they don't use the nanites thing as I'm not too crazy about the carry over of bad ideas from the first film. But not only is there the wounded problem for Stormshadow but that whole problem of how quickly water that cold can kill. Ha ha, unless they have the idea of zombie ninjas since the guys from Zombieland are writing the script.
