The last few seconds of the episode are definitely indication that there is a ticking time bomb that is about to explode. They haven't been shy at all about calling Walter "explosive" or a "time bomb".
I couldn't believe it's only been a year in their lives. During the course of a year, Walter has gone from a fumbling, submissive personality...to a full-blown narcissistic, morally corrupt, alpha-male. Skyler has gone from a loving, caring wife, to a manipulative, calculating cheater, and then to a dead-soul, hopeless, submissive type. Walter Jr. has gone from liking pancakes, to cereal.