What profession is the most promising in the next 20 years?(nursing)?

I would say that nursing is a profession that definitely has a bright outlook for the future. (I am a nurse with 17 years experience).
There will always be a demand for good RNs and right now I can't think of that many other professions that have the freedom nurses have. Once you become a RN you have so many choices. You can work in a hospital in an ER or birthing area, work with children or the elderly. Hospitals are also becoming creative with scheduling to recruit and retain nurses. Some of the units I have worked on did what was called "self-scheduling." The unit manager would give us a blank schedule for the next month and allow us to fill in when we wanted to work and when we wanted to be off.
Some nurses work what is called the weekend only schedule which was nice for those people that wanted to be off during the week (good for parents with small kids in school). Nurses can also work as a traveling nurse where they take 13 week (or longer) assisgnments around the country where they get paid a salary, plus housing, travel expenses, etc.
If hospitals are not your thing, there is always home health care and public health care as an option. Nurses even work in prisons. Some prison nurses in California are making between $90-100,000/yr.
Pay could be better, but I have seen some significant increases in the last few years. Pay also depends on the area you work. It is usually higher in a hospital setting.

Nursing is demanding right now
RT will be demanding in 5-10 yrs.
I'm doing RT program right now, i will graduate in 2 years.
nurses deal with the whole body, head to toe. (i have a friend in Nursing program)
RT deal with the head and thoracic and abdomen cavity. we will also look at how the hands and feet look depending on the symptoms of the patients.
to me RT is a little less rigorous then Nursing.
if you are considering career options then go to the hospital and talk to a few nurses and RTs and other medical professionals to get a better face to face interview.