Pfizer (PFE 0.67%) stock has been struggling for a while now. In the past 12 months, it has declined by 36%. A lack of growth recently, a dependence on acquisitions, and many question marks have resulted in a lot of investors simply taking a pass on this top healthcare stock.

But could that be a mistake? Could Pfizer return to glory in 10 years and prove to be a great buy again? Here's where the business may be a decade from now, and whether investors should consider buying the stock today.

Oncology is likely to play a much bigger role

A decade from now, the makeup of Pfizer's financials is likely going to change significantly. It'll be a surprise if its COVID vaccine generates any meaningful revenue, as concerns relating to the illness are already subsiding today. In 2023, despite a mammoth 70% drop in sales, Comirnaty was still the company's top-selling product, bringing in more than $11.2 billion.

But in 10 years, it'll likely be the oncology business that's the cornerstone of the company. Last year, oncology revenue totaled $11.6 billion, with breast cancer drug Ibrance leading the way with nearly $4.8 billion in sales. Pfizer has grander plans for its oncology segment with its huge $43 billion acquisition of Seagen last year, a company that makes antibody-drug conjugates, which are supposed to be more effective than conventional cancer treatments while also having fewer side effects.

By 2030, Pfizer believes that Seagen will add as much as $10 billion in revenue to its top line. In 2021, Pfizer also made a much smaller $2.3 billion acquisition of clinical-stage company Trillium Therapeutics, which has a portfolio of biologics that aim to utilize the immune system to destroy cancer cells.

Oncology is already a big part of Pfizer's business today, accounting for 20% of revenue, and a decade from now I wouldn't be surprised if it becomes its largest segment. Cancer remains one of the biggest concerns in the healthcare industry, and if Pfizer is successful in helping bring more effective treatments to market, it will be a win for not just investors, but for everyone.

Revenue and earnings will likely bounce back

In the short term, it's easy to be pessimistic about the company's future as its revenue growth looks lackluster. Pfizer is facing multiple patent cliffs, with key drugs such as Eliquis, Vyndaqel, and others all likely experiencing declines in demand over the course of the next decade as they lose patent protection.

But this is par for the course in healthcare. Companies need to build out their businesses to be versatile enough and have strong enough pipelines where they are always innovating and growing. As good as a treatment is, there will be an inevitable patent cliff in the future and competition to worry about.

Pfizer has been a top name in healthcare for decades because of its ability to innovate and find new ways to grow. I'm optimistic the company can get back to growing as its pipeline features more than 100 trials ongoing as of the end of January. Pfizer has also been investing through many acquisitions to strengthen its portfolio.

And with $12.7 billion on its books in cash and short-term investments, plus the company still projecting a profit this year, Pfizer's financials still look strong enough to allow the business to invest in more growth opportunities down the road. All of them won't pan out, but in healthcare all it can take sometimes is one or two promising blockbuster drugs to transform a business. Pfizer's investments into research and development and in acquiring promising businesses could pay off for investors in the long run.

Should you invest in Pfizer stock today?

Pfizer's stock is trading at only 12 times its estimated future profits based on analyst expectations. It's not an expensive stock by any stretch as investors appear to be discounting it based on the uncertainty that lays ahead for the business.

But Pfizer isn't as risky as it looks. The company is still in good shape, and could make for a great long-term buy. It may be a bumpy ride ahead, but in 10 years this could be a much more diversified business. With many growth opportunities to pursue, Pfizer isn't a stock I'd be too worried about in the long run.