I think the number of teachers is much more affected by demand than supply. You can't be a teacher unless people want to pay attention to you. I had an experience that blew those gates clear off their hinges, and into the nearest ocean. But I'm not teaching, and nobody's asking. My best friend was vaguely interested for one conversation over coffee, while we were sitting around waiting for something else. Everyone other than her was far less interested than that. How many people express that they're looking for more? How many act like they know just who they are and what they're doing? The world only has attention for a relative few dalai lamas or Eckhart Tolles.
Interesting, an old friend, whom I, and a couple of established Zen teachers (Rinzai and Soto) view as hugely awakened, sat a single weekend retreat, which he left due to aforementioned pain in the knees.
Apparently he tooks loads of LSD in his late teens, enough to drop out of college, literally grab a blanket and head into the woods for 6 months (verified by mutual friends).
That's a pretty "old" school approach ;-)
In the couple of years that I knew him he routinely blew my mind with in-the-moment koans.
FWIW, a brilliant mathematician and programmer who gave up silicon valley money for a non-thinking form of employment so he could more fully contemplate the magnitude of death.
