Source: Covered California. 

The Affordable Care Act, or Obamacare as it's probably better known, had a rather topsy-turvy first year. It fell far behind enrollment projections for a few months, then surged ahead and surpassed those estimates by the end of March.

But, what could year two have in store for Obamacare with regard to the number of new enrollees we can expect? That's the exact question we posed to three of our healthcare analysts, and here's what they had to say.

Sean Williams: Obamacare started out as the ugly duckling last year with multiple IT-architecture issues in October and November, but came out as beautiful as a swan with more than 8 million enrollees by the time open enrollment closed at the end of March, of which 7.3 million are still paying members.

But, what could 2015 hold in store for Obamacare?

In spite of improved education surrounding the health reform law and both insurers and health exchanges appearing better prepared to deal with an influx of enrollees, I'm going to take the under on the current 5 million-6 million enrollee estimates and bet on roughly 4.5 million new members.

Why the pessimism considering the strong finish in 2014? I have a two reasons in particular.

To begin with, I don't think we can overlook the fact that mid-term elections are pushing the start of open enrollment back more than six weeks. Furthermore, the end of open enrollment is also six weeks shorter for 2015. In total, consumers will be working with just three months to pick out an insurance plan in 2015 compared to six months this year. That time constraint, especially since it falls during the holidays, could prove troublesome.

Secondly, enrollees this year are going to be much tougher to convince to sign up. Although penalties for violating the actionable component of the Affordable Care Act, known as the individual mandate, call for a steeper penalty that's the greater of $325 or 2% of an individual's annual income, these penalties are still less costly, in most cases, than signing up for a full year of health insurance. Between young people resisting the urge to enroll because of the perception of invincibility and language barriers where English may not be the first language of other legal citizens, reaching many of these remaining uninsured could be a challenge.

Dan Carroll: With 7.3 million paying enrollees, Obamacare's first year was a big win -- but the Congressional Budget Office's aim of 13 million participants in the program after this year's sign-up period will be a tough goal to meet. With a number of challenges still in play for the young healthcare policy, 3.5 million-4 million new enrollees this year looks like a safe wager.

Source: Flickr user Francisco Osorio.

To be sure, Obamacare's come a long way since its troubled, technology-plagued launch last October. Healthcare.gov has had much more time for testing as compared to last year's glitch-ridden rollout. Additionally, the Department of Health and Human Services notes a 25% increase in insurers offering plans this year, opening up consumer selection.

Despite that, Obamacare's facing one major hurdle in round two that wasn't a problem last year. The Americans with the greatest need for healthcare likely took advantage of last year's open enrollment, taking most of the low-hanging fruit off of the market. The program will likely struggle to lure in less-motivated enrollees, especially as Obamacare premiums are expected to rise by 7.5% on average, according to a PricewaterhouseCoopers study. 

Additionally, the three-month enrollment period -- half as long as last year's -- runs right through the holiday season, with less time in the new year (when most of last year's enrollment occurred) for enrollment. Add that the ACA's remained unpopular overall with Americans in polls, along with a reduced media blitz in year two of the program, and Obamacare could struggle to repeat its first-year success.

Todd Campbell: OK Sean and Dan have taken the under, so I'll take the over. Sure there will be struggles, but I'm a bit less pessimistic than you two. In fact, I wouldn't be surprised if the CBO's estimate of a total of 13 million people being covered through the exchanges doesn't work out to closer to 15 million next year.

Source: Covered California.

Why am I optimistic? There's no question that health insurance costs are high, but as people begin to fill out those schedule 1040 tax forms I feel they'll decide paying for insurance and getting something in return is better than paying out more in taxes -- especially given that the fee for foregoing insurance will at least double next year. A bigger incentive than the public's general disdain for sending money to Washington, however, may be fear of being caught without coverage in the face of daily news trumpeting increasingly global health risks.

If lessons learned by the states and healthcare.gov can be leveraged to directly engage the uninsured with marketing that heralds the fact that nearly 80% of people getting insurance through exchanges will receive subsidies, then I think the administration will surpass its goal. Especially, since so many insurers who took a wait-and-see approach last year, including UnitedHealth (UNH -0.26%), will be offering plans on more exchanges this year. It's major insurers like UnitedHealth who will most effectively market the benefits of exchanges to potential members.

We also can't forget that while many of the low-hanging fruit signed up in the first year, there are still a lot of people who have lost their coverage in the past year as employers have reduced hours or limited benefits. Regardless, with about 40 million people still lacking health insurance, is it really a stretch to assume that the exchanges can have 15 million paying members that are unwilling to play roulette with their health next year? I don't think so.