Here's the economic reality of anti-cavity pills/gels/agents in general. There will be a cost associated with them, and more than likely due to the ability to transfer bugs from person to person, if you remove all the bad bugs from one's mouth, sooner or later, some spit will be swapped with a person who has the bad bugs and you've been "re-infected" and will need another dose. Chances are this won't be an over the counter drug/agent, so it will then come down to will people be willing to pay for it?? Or more than likely people will be asking if their insurance company will be willing to pay for it??
What the insurance company will do is take a look at the yearly average cost to cover their clients with this anti-cavity agent vs. what the yearly average cost for restorative dentistry is their clients. If the yearly average cost is less for restorative work (which it likely would be), then the insurance company WON'T cover the anti-cavity agent and the vast majority of people WON'T choose to spend the $$ out of pocket for it. That's the economic reality of how a large portion of the general public thinks. So I wouldn't worry too much about not having to use the handpiece to prep and restore teeth anytime soon!