Odds of Hanging On
Once you've completed your training, you should be set for life; it's not like an 8,000-year-old practice is going to suddenly be revolutionized during your lifetime. Excelling, however, will be reserved for only a special few who really embrace the lifestyle.
Those with good business sense and excellent communication skills are likely going to go the farthest, as running your own clinic and keeping your patients around are the two fundamental building blocks of success here. Duh.