Tenure in higher ed is gradually being squeezed out by academic administrative greed. Ironically, however lefty academia is, money is their motivation. Like any other business, they want the best product at the lowest cost. Non-for-profit is no different from business, since administrators took over the thing.
Tenure will only endure where it is least justifiable; in unionized government schools: The End Of Teacher Tenure?
Tenure, I suppose, used to be a substitute for high salary, but that no longer applies. Guaranteed job plus high salary plus great benefits no longer exists in the real world. Outside government jobs, that is. Why is that?