I completely disagree. First Trevor died, then it was Claudia that died. That effectively ended the Zs as a family unit and Johnny was on borrowed time. Then they constantly had him at war with Sonny--not a good career move while being written by Guza. This regime put the noose around his neck with the killing of Hope and Anthony, and the framing of Luke and Tracy and his manipulation of Connie, but that is because there was nothing left to the character by the time they arrived.
Exactly! This was his exit because the time had come (3+ years ago), and the only sad part is that his exit story turned into Todd's story.