You can get adjuncts and undergrads to be replacement TAs, but from my 2nd-hand experience via my wife (PhD in psychology) it would be research where things fal

You can get adjuncts and undergrads to be replacement TAs, but from my 2nd-hand experience via my wife (PhD in psychology) it would be research where things fall apart. The tenured professors rely heavily on PhD students to run grant-funded research and write papers for the lab. The general public thinks first and foremost about education, but for lots of academics, teaching is a necessary evil and research is where the prestige (and money) is.