I hope to have the chance to fly full time at some point - whether instructing or otherwise.
Seems to me that the only way someone of maturish years (I'm 40 now) can make a half-decent living in aviation is to get all the bells and whistles for CPL/Multi/IR training or shell-out megabucks for a type rating and take their chances.
In the meantime its part-time flight instruction only until the day that I acheive the above, or a bog standard FI can expect to earn at least as much as a bog standard driving instructor.
That surely wouldn't be too much to ask?