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No matter what you think of Affordable Care Act, there's no denying that healthcare has been a high-flying sector since the law took effect. No major index of large cap stocks has packed more punch  since Obamacare became law then the Health Care Select Sector SPDR ETF (XLV 0.04%).  

But the sector has shared the S&P 500's rocky start to the year, with the Health Care Select ETF sliding over 8%  year-to-date. Some pundits believe that's just a taste of what's ahead. After all, with a presidential election looming, virtually all the GOP candidates have made it clear they would be perfectly happy to sign a repeal bill. For his part, Democratic contender Bernie Saunders wants a single-payer system, something Obamacare doesn't achieve.

Predicting the future is always a roll of the dice, but I'd opine it's safe to say the fundamental demand for healthcare is headed skyward. The number of seniors in the United States should increase 36% this decade, with more than 20% of Americans over 65 by 2020. That's an unprecedented surge in the population that consumes the most healthcare products and services -- regardless of the fate of Obamacare.

Balance sheets in the healthcare sector are also flush with cash, which should increase the possibility of higher dividend payments, share-enhancing stock buybacks, and a continued wild boom in M&A. In fact, setting political viewpoints on healthcare aside, doomsday doesn't hang over healthcare stocks if Obamacare fails. Instead, there may even be new opportunities for investors. Starting with the big picture and drilling down to specific stocks, we asked three Motley Fool contributors what they believe could follow a rollback or major reform.

Sean Williams: Although nothing can be said with any certainty, I'd call it highly unlikely that Obamacare (officially the Patient Protection and Affordable Care Act) will fail in 2016. The primary reason is that the 2016 presidential elections won't usher in a new Congress and president until early in the following year. If legislation to repeal or alter Obamacare is going to make it through Congress and onto the new president's desk, it's not happening until at least Q1 2017.

However, that doesn't mean certain aspects of Obamacare aren't in flux. For instance, health-benefit providers that are losing money received just 12.1% of the $2.87 billion they requested. The lack of funding for the so-called "risk corridor" that's designed to protect money-losing insurers is a yellow flag for the long-term durability of Obamacare. Furthermore, the rapid rise in premium prices in 2016 caused by the closure of more than half of Obamacare's approved healthcare cooperatives suggests Obamacare may be doing little to control medical cost inflation despite a lowered rate of uninsured adults.

If Obamacare does find itself on the chopping block when the next president and Congress take office, I can't think of a company that would be happier than UnitedHealth Group (UNH 5.22%), the nation's largest health insurer.

UnitedHealth has been reaping substantial profits from Medicare Advantage over the past decade, but it also counts on the individual insurance market to drive its profits. UnitedHealth, though, has had no luck on Obamacare exchanges. In fact, the company lowered its full-year 2015 profit forecast on the heels of losses stemming from its Obamacare plans. For the time being, UnitedHealth has stopped advertising marketplace plans and could even pull its plans out of Obamacare marketplace exchanges by 2017.

Removing Obamacare would make cost comparisons of plans somewhat opaque once again, allowing UnitedHealth to use its size to its advantage in gaining new consumers. There's also the possibility that Obamacare's demise would allow insurers the ability once more to deny coverage to consumers with certain pre-existing conditions. Morally, this isn't something to cheer about, but it would almost certainly allow UnitedHealth to improve its pricing power and medical loss ratio (i.e., the percentage of premium money it spends on medical care for its members).

Todd Campbell: If Obamacare is tossed aside, millions of consumers who have become used to comparison shopping for their health insurance may turn to private health insurance exchanges that are run by companies including Aon plc (AON -0.37%).

Private health insurance exchanges are already seeing membership grow. Employers are embracing these plans in order to cut costs and boost choice for their employees. Workers at Walgreens Boots Alliance, for example, can choose among plans with coverage that ranges from minimal (bronze level) to expansive (gold level), depending on their insurance needs and their budget.

Enrollment in health insurance plans offered via private exchanges doubled to 6 million last year. If these exchanges were to become more widely available in a post-Obamacare America, then Aon and its competitors could end up benefiting from a natural tailwind of accelerating sales and profit.

If Aon's big and diversified nature isn't necessarily in keeping with your risk-tolerant investment style, then it might also be worth considering eHealth, a small-cap, debt-free insurer that also offers insurance to individuals and employers via private exchanges.

Cheryl Swanson: How much does the medical device industry hate Obamacare? Enough to spend over $150 million in Washington the past five years, trying to kill it. Heading the list is Medtronic (MDT -1.22%), now the largest medical device maker in the world. Medtronic was the biggest spender on lobbying against the ACA last year, with its chief target Obamacare's 2.3% medical device excise tax, which is estimated to cost the industry $29 billion  between 2013 and 2023.

While that's a staggering sum by anyone's estimation, Medtronic and other major device makers have continued to log record profits. How? In the short term, that's because Medtronic, like Johnson & Johnson, has been able to pass the cost along by increasing the price of medical devices. Those increases haven't led to an outcry because doctors as well as patients rarely know the cost of medical devices. While this may sound incredible, according to a recent Health Affairs survey, 80% of surgeons don't know the price tag of the hip and knee devices they are implanting.

On the long term, the rise of Accountable Care Organizations (ACO)'s will undercut the ability of device manufacturers to shift the cost of the tax to consumers. Not only is more cost transparency coming to American healthcare, but healthcare provider networks will eventually be penalized if they don't meet cost and performance benchmarks. The impact of Obamacare is complex, but medical device makers will face increasing margin pressure -- which makes them key beneficiaries of a possible repeal.