Image source: Illumina.

Last year ultimately proved to be something of a dud for Illumina (NASDAQ:ILMN). Shares of the genomic sequencing company ended 2015 up a paltry 3.5%. Illumina missed revenue expectations in both the second and third quarters. We'll find out later in January how the fourth quarter of 2015 turned out. But could 2016 be much better for Illumina -- even the best year yet? Here are three keys for Illumina to experience a banner year.

1. Payers pivot
Illumina received great news in August 2015 when Anthem (NYSE:ANTM) announced a major change in reimbursement policy for non-invasive prenatal testing (NIPT). In the past, the large health insurer only viewed NIPT as medically necessary for high-risk pregnancies. Anthem reversed course, though, and now reimburses for NIPA in average-risk and even low-risk single-fetus pregnancies.

Anthem became the first major insurer to approve reimbursement for NIPT outside of high-risk pregnancies. And it did so despite a lack of scientific consensus on the matter. There are some studies that support the use of NIPT for pregnancies that aren't high risk, but these studies aren't universally accepted because of design limitations including low sample sizes.

The big question for Illumina and others in the NIPT market now is: Will other insurers follow Anthem's lead? If they do, there's a lot more money to be made by Illumina and its rivals. The average-risk NIPT market is estimated to top $2 billion.

2. Desktop delivers
Desktop sequencing sales stood out as a glaring weak spot for Illumina in the third quarter of 2015. Revenue for both MiSeq and NextSeq were lower than expected, with MiSeq sales actually dropping slightly year over year. If Illumina is to have a great year in 2016, desktop sales need to improve.

One key to making that happen is improvement in Asia. In particular, Japan should present a good market for MiSeq. However, the funding for genomic sequencing technology hasn't been strong in Japan for over a year. Illumina thinks that situation could change in 2016.

There's also a potential China challenge. Life Technologies, now part of Thermo-Fisher Scientific (NYSE:TMO), was first to bring a desktop sequencing system to market with its Ion Personal Genome Machine. Thermo-Fisher reported excellent results in the third quarter from its Chinese operations, while Illumina's CEO acknowledges that his company doesn't have as strong of a presence in China.

Still, though, Illumina doesn't seem to have reason to be too worried about competition from Thermo-Fisher or other rivals. Illumina says that its head-to-head win rate against rivals in the desktop market is holding steady at more than 80%. If the company can sustain that rate and see improvement in Asia, 2016 should be a good year.   

3. Cancer conquests
One of the brightest areas for Illumina in 2015 was the strong growth in adoption of its technology by clinical customers. Adoption by oncology customers especially drove this growth. For 2016 to become Illumina's best year yet, this trend needs to continue.

Illumina thinks oncology could present a $12 billion market. The company seems to have a solid strategy for going after this market. Illumina's TruSight Tumor 15 product is the first fruit from this strategy. The product uses next-generation sequencing to assess 15 genes that frequently have mutations that cause cancer.

What about the "holy grail" of cancer screening: early detection of cancer via blood testing of individuals who don't yet exhibit any symptoms? Illumina recently announced the launch of a spinoff company, appropriately named Grail, to tackle this challenge. Grail even attracted a couple of investors you might have heard of: Bill Gates and Jeff Bezos.

Don't expect Grail to make a big impact for Illumina in 2016, though. Illumina thinks the revolutionary cancer test won't be ready until 2019 -- and that timing could prove to be overly optimistic.  

Best year yet?
So, will 2016 emerge as the best year yet for Illumina? I'd say it's doubtful.

There's a really high bar to jump for 2016 to become the best on record. Consider that Illumina's stock has more than doubled in three of the last 13 years and nearly doubled in a fourth year. I just don't see enough catalysts to think Illumina could come close to doubling this year.

Don't get me wrong, though. I suspect Illumina could do quite well in 2016, assuming the overall market doesn't end up being quicksand for nearly every stock. And over the long run, especially if Grail hits paydirt, Illumina should continue to be a big winner for shareholders.