There aren't many coaches who are in similar positions to Sullivan. Like it or not, his status as a two-time Cup winner changes the conversation. The closest comp is Cooper, who was head coach for six years, missed the playoffs one of those years and suffered an embarrassing sweep at the hands of Columbus another year, before he finally got Tampa over the hump and won a Cup.
Cooper's job wasn't in question.
Barry Trotz lasted 15 years in Nashville without ever getting to the conference finals.
Quenneville was fired in Chicago and could be a comparison, but he had numerous clashes with management that became public.
Finally, Bylsm and Sullivan aren't in the same position. Bylsma lost the room. By all accounts, the core still likes Sullivan. Bylsma also had the core in its prime. There was a greater sense of urgency. Sullivan is coaching them in their final years.
Firing Sullivan may ultimately be the right move, but his situation isn't really comparable to others.