GoPro (NASDAQ:GPRO) stock has fallen by more than 50% since early August, as the market has grown increasingly pessimistic about GoPro's sales growth. Many observers have also flagged concerns about GoPro's longer-term ability to fend off competition.

GoPro YTD Stock Performance, data by YCharts.

Last week, the company released a new mid-range camera -- the HERO+ -- at $199.99. This camera features Wi-Fi capability and better image quality than the entry-level $129.99 HERO camera.

This product launch also served as a backdoor announcement that GoPro won't be launching any more new cameras this year. That confirms many investors' fears that GoPro wouldn't launch a new high-end camera in 2015. What does this mean for the company's prospects?

The HERO4 Session fizzles
In July, GoPro launched the HERO4 Session: an ultra-compact action camera that is 50% smaller and 40% lighter than the company's flagship HERO4 Black camera. With a lofty MSRP of $399.99, the HERO4 Session was apparently meant to be GoPro's new high-end camera for 2015.

Demand for the HERO4 Session has missed expectations. Image source: GoPro.

However, demand for the HERO4 Session hasn't lived up to expectations thus far. GoPro CEO Nick Woodman has attributed some of this weakness to continuing strong demand for the HERO4 Black and HERO4 Silver. He suggested that the Session has had trouble standing out from GoPro's other top-tier cameras.

At an investor conference last month, CFO Jack Lazar elaborated on that point. He noted that the HERO4 Session is a lot different from GoPro's previous cameras. It's much smaller and simpler and thus has different strengths than the company's other offerings. Lazar suggested that GoPro may ramp up its marketing and in-store training to better explain the benefits of this camera.

That said, GoPro seems to have ratcheted back its expectations for the Session. In the press release announcing the HERO+, GoPro also dropped the Session's MSRP by $100, putting it at a more mid-range price point of $299.99.

The holiday outlook
While GoPro's HERO4 Session has fallen short of expectations, this isn't as big a problem for GoPro as many investors seem to think.

First of all, the HERO4 Black and HERO4 Silver cameras are still selling well. In Q4, GoPro will face some very tough comparisons, as these two popular cameras went on sale last October. Without meaningful upgrade demand, there's a good chance that GoPro's U.S. revenue will decline year over year during the holiday quarter.

However, GoPro has huge growth opportunities abroad. Indeed, 57% of GoPro's 2014 revenue came from the U.S. alone. The company was just getting started in many emerging markets in Q4 2014 -- the HERO4 lineup didn't arrive in big markets like Brazil and China until this year. Those products could sell quite well abroad this fall, despite being somewhat stale in the U.S.

The HERO4 Black wasn't available in some major markets last fall. Image source: GoPro.

Meanwhile, even though GoPro's high-end camera sales in the U.S. will likely decline in Q4, it could make big gains in the mid-range market. In addition to the $199.99 HERO+ introduced last week, GoPro also launched the $299.99 HERO+ LCD in June. Lastly, the HERO4 Session could garner more interest at its new $299.99 price.

Looking ahead
While shareholders would obviously like to see GoPro's revenue growth continue in Q4, long-term investors should be more concerned about its pipeline beyond 2015. A quarter or two of stagnant (or even declining) revenue in the midst of a long-term uptrend isn't really something to worry about.

The drone market could be GoPro's biggest growth opportunity in the next few years. GoPro is on track to begin selling its first drone in the first half of 2016. As I have previously noted, that is also a likely launch time frame for the next-generation high-end GoPro lineup. That in turn could reinvigorate the growth of GoPro's action camera business.

Finally, GoPro is continuing to build its brand. This has primarily centered on building a massive social media presence and encouraging the sharing of GoPro videos. More recently, GoPro cameras played a big part in The Martian, a new movie starring Matt Damon that has performed extremely well at the box office since opening last week.

The market has unreasonably punished GoPro for what is still only an expected hiccup in sales growth during the fourth quarter. GoPro could easily beat Wall Street's pessimistic expectations as it has often done since going public last year. Even if it doesn't, growth is likely to reaccelerate in 2016 as GoPro kicks off a new product cycle -- and that could reignite the stock.

Adam Levine-Weinberg is long January 2018 $30 calls on GoPro. The Motley Fool owns shares of and recommends GoPro. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.