If it feels like you've seen this movie before, it's because you have: Facebook (NASDAQ:FB) is -- once again -- losing its luster among the all-important teen crowd. U.S. teens, described as 13- to 17-year-olds in a recent study, aren't exactly leaving Facebook in droves, but usage has declined from 95% in 2012 to a "mere" 88% this year. By comparison, teen users of Twitter (NYSE:TWTR) grew 2% this year compared to 2012, and is now used regularly by 48% of America's teenagers.

The angst involving Facebook teens leaving is nothing new; the back-and-forth as to whether younger users are on the site has been going on for well over a year. Despite Facebook CEO Mark Zuckerberg directly refuting the teen "problem" as far back as Q2 of 2013, here we are again rehashing usage concerns. Thing is, whether Facebook is or isn't actually losing teens really doesn't matter. Sure, if youngsters were leaving Facebook by the millions that might be cause for concern, but that's not the case. As for the relatively few that are? Facebook has a plan for that.

What's the problem?
Teens included in the recent report pointed out a couple of reasons for not logging on to Facebook as often. Like a lot of things that have become popular, and stayed popular, over a long period of time, Facebook just isn't "cool" anymore among the "what have you done for me lately" teen crowd.

Cool or not, as Zuckerberg points out, "[W]e've [Facebook] been fully penetrated in the teen demo for a while now." In other words, when most every U.S. teen with Internet access is already using the site -- and even the "drop" to 88% is impressive penetration -- there are few places to go but down. Of course, as more emerging markets come online via Zuckerberg's Internet.org initiative, global teen usage is likely to soar, regardless of American teens.

Another concern cited by teens is one that's echoed by a growing number of Internet users, not just Facebook "friends," and that's security. A paltry 9% of teens included in the recent study said they thought Facebook was "trustworthy," compared to 30% who described social media alternatives like Pinterest as "safe." It's likely Twitter, and most every other online site, would score relatively low on the trust meter, too, no matter the demographic.

The solution
As Zuckerberg points out, the demise of Facebook among teens is exaggerated, but even if it were the case, the social media behemoth has several tricks up its sleeve. Facebook's fast-growing Instagram -- it recently surpassed 300 million monthly average users (MAUs) -- has one of the youngest demographics of any social media site. Twitter may have 48% of U.S. teens actively using its services, but considering the tweet master's anemic growth curve, it won't be long before Instagram dwarfs it both in size and among the world's teens.

Another social media favorite of the teen crowd is also a Facebook property: WhatsApp. With 700 million MAUs, and growing, Facebook's just fine with teens gravitating toward the messaging service. Now toss in Facebook Messenger and its 500 million plus MAUs, many of whom are teens, and any perceived "problem" with Facebook's demographics goes out the window.

Whether intended or not, Facebook's relatively new properties Instagram, WhatsApp, and even its Oculus Rift virtual reality headset, are all ideally suited for today's teens. While some younger users will shift loyalties to the Twitter's of the world, teens ditching Facebook just doesn't matter because they're still under the same roof; they just moved to another room.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.