The CWConsidering how extravagant and well-thought out some of these theories are, its a little disappointing to think that the show may have just straight-up told us the main cause of whats going on. As Barry suspects, Zoom is dying as a result of his dependence on velocity and he needs Barrys speed to live. The idea that its just as the episode said seems a bit simple, and as of now, its just a thought that Barry has based on the blue lightning he saw around Trajectory before she vaporized herself. One crucial detail that makes this plausible is that it would go a long way to explaining what Zooms goals are. He doesnt have a typical bad guy plot and in this scenario, he would literally only be trying to save himself. Reverse-Flash had similar personal goals last year, and it worked so well that maybe it made sense to keep the villains methods large but his purpose intimate once again.