It does seem like there's a glut of adjuncts, especially for liberal arts. I've always viewed adjuncts as just what some professionals do as a side interest or to pad a resume. Don't know why someone would look at it as a career. Besides, I'd guess that there is little movement among the tenured professors. So if you're an adjunct waiting for an opening, you'll probably be waiting for a long, long, time.
As long as adjuncts are available for low wages, there won't be any openings for tenured professors. That's the point of hiring adjuncts.
The oversupply of advanced degrees in liberal arts was predictable. If a person gets an engineering or business degree, they can expect to find a job as an engineer or manager. There is no such thing occupation as "liberal artist."
In the beginnings of our modern University system of education, colleges produced ministers. A graduate of any of the Oxford colleges was qualified to be a priest of the Anglican Church. The liberal arts study was conceived to give the sons of rich families enough education to prevent them from becoming ignorant boors. It was never intended to be the foundation for a career. These men were never going to work for a living.
These days, colleges pump out English majors and Art majors by the millions, the sons and daughters of the rich, the middle class, and the poor alike. There will always be a need for a certain number of liberal artists, but never that many.
Sooner or later, reality will need to be faced. There is no reason to to work for a degree, which does not qualify a person for a job that pays well enough to pay back the loan which paid the tuition.