There are some ways to have no tenure without it being awful. My teaching track appointment, for example, is on a rolling 5 year contract; each year, if I am deemed to be doing a satisfactory job, the end date moves out a year. (I got to this after years of 1-year-at-a-time).

But if academia were to move to a fully tenure-free system, I expect there would need to be a significant change in salaries. The idea of a fully dependable job for the long term is a substantial benefit; giving it up would mean something else would have to be available.