Boy, a bit more enthusiasm here for this idea than I expected!
Thanks for the positive feedback, everyone.
Since I have y'alls attention, perhaps I can get you to serve as an unpaid "focus group" for me.
In no particular order, here's what I've been considering/questions that I have:
1) How much time are people willing to commit? To make such an online course a true value, I figure that it would need to move beyond just the half-day of lectures on exercise physiology that is part of USA Cycling's level 2 coaching certification. OTOH, I don't think it would be possible to go into tremendous detail, as A) not everyone signing up for such a course necessarily has the background that would be expected of an undergraduate exercise science student, and B) only so much detail is really useful to a coach (versus interesting). Just off the top of my head, then, I was considering 1.5 h/wk for 10 wk, or perhaps 2 h/wk for 6 wk. As potential student/clients, does that make sense/appeal to you?