Vaccine sales have been on the decline, so you may think it's too late to buy Pfizer (PFE -0.97%) stock. After all, the big-pharma company is the vaccine leader and its vaccine brought in a whopping $37 billion in revenue last year.

From the start of the vaccine race through 2021, the stock advanced nearly 60%. Since then, however, it's slipped about 29%.

At the same time, some of Pfizer's biggest drugs are set to lose exclusivity within the next few years. Still, the pharmaceutical giant isn't just sitting around and waiting for sales to fall. It has a plan and already has taken action.

Does this mean there's still time to buy Pfizer stock and benefit down the road? Let's find out.

Falling from a high

First, let's consider the coronavirus part of the picture. We're heading into a post-pandemic situation. As a result, sales of Pfizer's vaccine Comirnaty and coronavirus treatment Paxlovid are set to fall from their highest levels. But that doesn't mean their contributions to revenue are over.

In fact, Pfizer says it expects both products to "remain multibillion-dollar revenue generators for the foreseeable future."

Pfizer and rival Moderna both predict the coronavirus vaccine market will follow that of the flu vaccine market. That means about half of Americans may go for an annual booster. At the same time, Pfizer and Moderna both have said they will lift their vaccine prices. As a result, they may continue to generate blockbuster revenue from their products.

Now I've got some good news and some bad news. We'll talk about the bad news first. Pfizer expects to lose $17 billion in revenue between 2025 and 2030 as major products lose exclusivity. One of these losses includes blood thinner Eliquis -- a key growth driver for Pfizer last year. 

The good news is Pfizer aims to compensate for these losses and even grow revenue further through its own pipeline and business deals. The company already is making significant progress. Pfizer expects to launch 19 new products or indications within an 18-month period as of now. This is a record for the company.

Of these possible launches, 15 come from Pfizer's own pipeline. And it expects them to generate $20 billion in 2030 revenue.

Pfizer also has made a number of acquisitions over the past few years. And from these deals, Pfizer expects to generate at least $25 billion in revenue in 2030. So, yes, Pfizer is heading for a slowdown in the near term. But major growth drivers are just around the corner.

Pfizer's valuation

Let's take a look at Pfizer's stock price. The company is trading at about 12 times forward earnings estimates. Today, Pfizer is in a phase of transition as the coronavirus market shifts to a post-pandemic environment and as it renews its product portfolio. So the stock may not seem like a bargain right this minute.

But if we consider the Pfizer of later this decade, all of a sudden today's price looks like a steal. And since we're interested in buying for the long term, now seems like a great moment to get in on the Pfizer story -- and benefit over time.

Meanwhile, you can bring in passive income if you own Pfizer shares. The company returned $9 billion in dividends to shareholders last year. Pfizer pays an annual dividend of $1.64 per share, and its dividend yield of 3.93% is above the average of the pharmaceutical industry.

It isn't too late to buy shares of Pfizer. In fact, right now is the perfect time to snap up shares at a very reasonable price -- and bet on the next phase of growth at this pharmaceutical giant.