20-Year Prospect
Standard medicine advances pretty quickly, but alternative medicine? Yeah...not so much. The whole idea of most holistic care is that it's old and has been passed down for centuries. Acupuncture goes back over 8,000 years (source), while using herbal remedies probably dates back to the caveman era. And if this stuff can survive that long, then twenty years is the blink of an eye.
Science has attempted to refute much of alternative medicine, and people have debated its purpose and safety since the discovery of penicillin. And yet, holistic healthcare is still standing. With nearly forty percent of the population using it in some capacity, it's not going anywhere (source). And nor, for that matter, is illness. So long as people keep getting sick, you'll be in business.