nowadays all kinds of music teachers are retiring and he constantly gets calls asking for new guitar teachers

I’d be skeptical about continued opportunities, as there might just be more demand for recommendations from a professor from a renowned music school, and he’d probably be more likely to recommend recent graduates, so you’d only gain that advantage until the next semester class graduates. Unless it’s for jobs in schools as opposed to lessons after school or something?

salaries are higher than what I earn now

Is that for jobs in schools, or after school lessons? (After school lessons might have a higher hourly pay but less frequent work, so not actually a salary but more like a contractor?)

I enjoy explaining organs to patients, and I’m not ready to simply ignore the last 7 years of my life

Have you considered making songs that explain organs? Maybe it could go viral 😅