That's the book, I doubt Igor is in any way related to Long Haul in the movie, he's a joke character for crying out loud I doubt the writer even put that much thought into him. And why is Megatron really dead? How bout his freakin spine was ripped out and his head was ON FIRE in the very last seen. Seriously we need to stop desperately clinging to him, I love Megatron but after DOTM I think it's well and truly time we got some fresh blood in the Con ranks.
Though there is nothing worthy of salvation in Meg's physical body, I believe his spark escape the massacre by Prime and floated to a nearby object (like a pistol perhaps to prevent it for being extinguished.
he should not come back and if a 4th movie were made bumblebee should be the villain and die at the end