[amark]

Nobody gets tenure anymore. Most stay as associate professors, and make 60-70k.

[santaclaus]

It's usually a big deal when a professor fails to make tenure at a respectable university. I can think of multiple case studies at MIT and Stanford. Departments look bad when they are forced to drop promising talent.

[Fomite]

It's becoming far more common.

More importantly, there are far more positions being created that aren't on tenure track in the first place.