This is a great question.
Here is the reality we have today and probably more of it in the future. The middle class in this country is eroding very fast, and the dental insurances they usually carry (PPO and such) will also follow.
Now, in the future, in terms of lower income and high income demographics, dentistry as a market will cater to those groups more. Obamacare expansion in my state alone added close to 800k people, and counting. Since Obamacare is going no where anytime soon (no matter how most dentists feel about it), there are a large management Medicaid groups entering and competing for the Medicaid contracts to cater such patients, and slowly more dentists will be moving away from PPO style insurances to Medicaid style insurances. How does this benefit these dentists? For start, there will be greater demand Medicaid style dentists, and in some states, Medicaid fees are 70-80% of some private insurance fees.
Medicaid had a lot of problems 10 years or so ago, from limited coverage in procedures, to longest reimbursement periods for doctors (30-60 days), which discouraged a lot of dentists to not accept it. Now, you have large Medicaid management groups changing the game, some are reimbursing doctors within 24-48 hours, prior authorizations approved within hours, and far less challenges than PPO insurances when it comes to large cases (dentures, crowns, etc).
On the other end of the spectrum, the wealthier segment of society will grow and focus more on implants and cosmetic services as fee for service patients, because those procedures are rarely covered by private insurances now and even less likely in the future. So you will see the dentists who cater to the wealthy having boutique style dental offices (I have seen one here in my town), who basically offer general dentistry services or specialist services at a uber fancy offices (with latest digital technologies and such).
The exception will be corporate dentistry, or chop shops/dental mills, who will push dentistry to a conveyor belt style system. It will be a place where people who don't see dentists or bargain hunters end up going to, because they found out about those offices through a 30 second commercial on TV or on their Facebook feed. It's where the potentially most unethical services meet the least informed segment of society in my opinion, if they are not already enrolled in Obamacare.
America is heading towards further economic segregation, and dentistry will follow that path as well.