to nug:
Personally I think restorative dentistry will still be around..
No matter how good public-health preventive measures get (fluoridation of water, sealant programs, etc.), there will ALWAYS be people who neglect their oral health. There will ALWAYS be young kids who do not know any better and go to bed after eating sweets without brushing their teeth. There will ALWAYS be accidents that cause traumatic injury to teeth-- People falling off bikes, smooshing into trees while rollerblading, what have you. There are fluoride-resistant strains of strep mutans out there now as well.
Same goes for older folks who neglect their periodontal health-- You can be sure there will be plenty of seniors who lost their dexterity, cannot brush/floss adequately, and consequently be afflicted with periodontitis, losing their teeth and requiring dentures. There will ALWAYS be smokers (smoking contributes significantly to periodontal deterioration). Also, RPDs and Complete dentures as a rule are usually cheaper than newer alternatives such as implants so you can be sure there will still be a market for them (just ask any dental residents working in VA hospitals!).
Restorative dentistry will still be around in 30 years, 50 years, or even 100 years from now, believe me.