In spite of market turmoil, this year has been bright so far for AbbVie (ABBV 1.06%). The stock defied the bear market -- and even gained more than 6%.

The company's star drug Humira continues to grow, and even reached the milestone of more than $20 billion in sales last year. Its other immunology drugs and the neuroscience business also are thriving.

However, there's one big problem on the horizon for AbbVie: Humira is set to face competition, as of next year. AbbVie hasn't yet forecast future sales for Humira, but it's clear declines are ahead. Considering this, where will AbbVie be in about three years? Let's find out.

The situation today

First, let's take a look at AbbVie's current situation. The company's top product -- and the world's best-selling drug -- is Humira. The treatment is used for a variety of conditions, including rheumatoid arthritis and Crohn's disease. Last year, Humira accounted for more than 36% of AbbVie's total revenue.

Still, AbbVie has plenty of other products to depend on. And about a dozen are blockbusters. The company sells treatments in areas of immunology, oncology, neuroscience, aesthetics, and eye care. In the most recent quarter, both the immunology and the neuroscience businesses grew sales in the double digits.

Now let's take a look at a few elements that will offer us clues about AbbVie's situation in three years. Humira already faces competition in other markets outside of the U.S. In the second quarter, Humira's international revenue fell more than 13%, due to this competition.

Each market is different, so it's impossible to pinpoint exactly how much Humira sales will fall in the U.S. But as mentioned above, we should be prepared for some declines.

At the same time, AbbVie's immunology drugs Rinvoq and Skyrizi are growing. In fact, they're growing so much that the company predicts their peak sales together will beat Humira's peak sales. And in 2025, AbbVie expects Rinvoq's and Skyrizi's combined sales to reach $15 billion, FiercePharma reported.

AbbVie is working toward the approval of Rinvoq and/or Skyrizi for all of Humira's major indications -- with the addition of atopic dermatitis.

Double-digit growth

AbbVie's neuroscience business includes drugs such as Qulipta for migraine and Vraylar for bipolar disorder. They've seen double-digit growth from quarter to quarter recently. And AbbVie is aiming for approvals in Qulipta for chronic migraine and Vraylar in major depressive disorder. That would expand revenue opportunities for those drugs.

Aesthetics also may continue to thrive. The global facial-aesthetics market, at a compound annual growth rate of 15%, is expected to reach more than $25 billion by 2031, according to Allied Market Research. And AbbVie sells two of the top brands: Botox and Juvederm.

Recently, Juvederm filler revenue slipped due to a few factors -- coronavirus restrictions in China, the halt of aesthetics operations in Russia, and a difficult-to-beat year-earlier quarter. Eventually, the situation in China will improve. And AbbVie plans two filler launches in the U.S. this year that should boost sales over the long term.

It's also important to remember that AbbVie has more than 40 candidates in the pipeline, and that's counting only new molecules. Marketed products, including some I've mentioned above, are involved in clinical studies for additional indications. About 20 candidates are in the phase 3 stage or already submitted to regulators. If even a few make it to approval, this could offer AbbVie's revenue a big boost.

The top prescription-drug company

Even with the loss of Humira's exclusivity, AbbVie may have many exciting chapters left in its story. In fact, AbbVie is set to become the top company, based on prescription-drug market share, by 2026, according to Evaluate.

What does this mean for you as an investor? In spite of AbbVie's gains this year, the stock still looks cheap. It's trading at only 10 times forward earnings estimates. That's compared to an average of about 24 for the pharmaceutical industry.

Investors who buy at this level -- or who already hold AbbVie shares -- may not regret their investment. AbbVie's pipeline and current blockbusters could keep this company growing in three years -- and beyond.