hello
is there a medical field/specialty that patients expect more to come in the future? where there is large need of new innovative therapies? where research is vast, where many aspects are unclear and many problems unsolved?
No harm in a little ambition. There are black boxes, mysteries, and hand-waving arguments that need to be described mechanistically everywhere in medicine. You just have to find out where the problems seem biggest to you.
Be patient, read up, and keep your eyes open. A good place to start is reading the lay literature (WIRED, Scientific American, the New York Times Science section, and so on) and dive in to the work of scientists that catch your eye there.
One current "new big thing" in genetics is "genomic medicine" or "systems medicine". The philosophy underlying this is that diagnosis, assessment of risk, and prevention are all cheaper than treatment of a full blown disease.
Those that believe in it say it will impact all fields of medicine. You can read a ton about it in the reviews of large association studies, the cancer genome project, and the systems biology literature. I recommend you read some of the criticisms as well. Biomedical research is a polyculture of ideas, and no one is right until almost everyone agrees.
Another that's huge in Seattle is Global Health. This is more multi-disciplinary than just science and medicine, but is also worth a look.
Another thing to consider: I personally think the biggest change underway in medicine is not in the technique, technology, or outcome per se, but rather in the transformation of the patient into a
(semi-)informed consumer. Patients everywhere in the US are starting to expect a slicker product.