It is NOT in demand. I live and work in Massachusetts. I graduated 4 years ago and have been barely working ever since! Most RDHs work part time and get NO benefits (not even health insurance). That means NO paid sick days (and when you call out sick they somehow expect you to be able to do that many days in advance which sometimes is impossible and you risk losing your job!) no vacation days (I was recently lectured by a dentist during an INTERVIEW how anyone he hires should never take a vacation and expect to work year round, since it is only a part time position offered).
I have now stopped looking for more RDH jobs cause I am sick of dealing with dentists and going to horrible interviews. One dentist actually YELLED at me for asking if he lets his RDHs do local anesthesia (this passed in 2004 or 2005 in Mass). He said NO! And was upset that I even asked! I only asked cause I was forced to take the course and get my LA license for RDH. I didn't care either way if he allowed it or not in his office.
I am trying to get a career out of this RDH field. I feel bad for RDHs since I know the job is tough and the rewards are less and less every year. Good luck to you.