<p>Well, you have to define shortage very carefully - the idea behind a "shortage" is that there are people who want doctors and are willing to pay a price that doctors would accept, except that doctors are simply too busy to take them as patients. By this standard, I would argue that a shortage currently exists, since some patients exist who would be willing to pay more for better care (i.e. appointments longer than 15 min) but cannot receive it in our current delivery system.</p>
<p>The shortage will only get worse over time, as HMO and government control tightens - particularly if Clinton-style health care is implemented, as I'm quite confident it will be within the next generation.</p>
<p>BRM is right that specialties wax and wane, but I think it's unlikely that any specialty in any area is currently experiencing a "glut" (doctors would be willing to practice at the market rate but cannot find patients), and I think the odds of such a glut will diminish considerably over time.</p>
<p>Slightly-less-invulnerable specialties might include diagnostic radiology, anesthesiology, and cardiothoracic surgery.</p>