my personal favorite method of checking out whether a field is dying or not is to go online and look for jobs
neurosurgery for example - plenty of opportunities, and these are the ones that are advertised on internet job-searching services. check out magazines, special classifieds, etc. not to mention the offers straight out of residency.
"dying out" is a very relative term. is a move into CT surgery a bad move? well, look at the number of jobs there are. but look at the number of people in it. it's like millions of openings for computer techies, consultants, etc. and millions of grads each year.
or about three hundred openings for nsg, CT, etc. per year, but only 100 new surgeons produced each year, with a significant veterans retiring. is the field dying?
its BIG NUMBER entering divided by BIG NUMBER openings or
its little number entering divided by little number openings
so again, is it dying? shrinking? maybe. dying? you gotta remember that 99% of the population can't even make it to medical school. now you're talking specialized surgery? 0.01% of the jobs out there for 0.001% of qualified people. the numbers are smalled, compared to, say, accountants, but, IMO, the demand is still there.
for repetition's sake, it's 5 applicants for 10 openings or 5000 applicants for 10000 openings. your average applicant in this pool of 5010 people would think "only ten openings!? good god that would have been a terrible career move. i'd stick to the job offering 10000 openings so i won't have to be jobless!" they forget that for those ten openings, only five people in his pool are qualified. so demand, in this case, is the same.