20-Year Prospect
While oral surgery might not sound as common as a trip to the dentist office, the profession is going steady. Just like any other kind of surgeon, oral surgeons provide a necessary service. Pain is your friend. If people's gums are starting to ooze from an impacted tooth, or their teeth ache every time you take a bite of food, they'll have no choice but to see you.
People's mouths need roughly as much surgery as they ever did. As a result, job growth rates for this career haven't changed much since 2004, and are expected to rise a respectable five percent in the coming years (source).
You may end up operating with lasers alongside robots twenty years from now, but the job isn't going anywhere.