If 2013 was the year of the app, then 2014 is shaping up to be the year of engagement. Nielsen  recently released the most popular smartphone apps for 2013. Below are the apps in rank order along with their monthly average user numbers:

RankCompanyMonthly Average Users (millions)
1. Facebook 103.4
2. Google Search 76
3. Google Play 73.7
4. YouTube 72
5. Google Maps 68.9
6. Gmail 64.4
7. Instagram 32
8. Apple Maps 31.9
9. Stocks 30.8
10. Twitter 30.8

King of the smartphone
First and foremost, Facebook (META 0.55%) killed it. But take a look at the top seven apps; they're owned by only two companies: Facebook and Google (GOOGL 1.87%). Total up the numbers and Facebook and Instagram garner 135 million monthly average users. But Google, with numbers 2-6, totals a whopping 355 million!

Now, of course, there's overlap here; those totals aren't the point. The point is consolidation, and we are sure to see more of it in the coming years. Google understands the value in offering more than just search and Facebook is making the efforts to be more things to more people as well. Hence the Instagram acquisition along with the failed efforts to acquire Snapchat and even Twitter (TWTR) back in the day.

The lines are being drawn
The big battle in the coming decade is going to be one of engagement more than anything else. Monthly average users are fine, but unless they're sticking around it doesn't really matter. Given that 60% of social media time today is spent on mobile (tablets included), it's reasonable to assume that this trend will only continue. And that's why Facebook will continue to focus on mobile engagement.

Instagram is a step in that direction and ultimately a good one. But Instagram is still unproven as far as monetization goes. Video ads will be another piece of the puzzle, but they'll need to strike the right balance so as not to ruin the user experience.

Twitter + NFL = Touchdown
Because Twitter's feed is based more on news-type content and real-time events, it's no surprise that media outlets are relying on Twitter as a platform instead of Instagram. It will certainly be interesting to see how Twitter and Instagram jockey their positions in the coming years.

The NFL Network, for example, is really nailing a wonderful Twitter experience with things like their replay tweets minutes after the play happens prefaced by a 6-8 second commercial from big consumer-facing companies like McDonald's and Verizon. Yesterday's tweet below is just one recent example:

Don't be surprised to see more media outlets and entertainment stalwarts employ similar strategies in the very near future.

The Foolish bottom line
The takeaway for investors in all of this is that it's important to remember social media is not a zero-sum game. It's not a "Facebook wins and everyone else loses" proposition. There will be multiple winners and Facebook, Google, and Twitter are all concepts that should be very relevant a decade from now. So, pan out and think bigger. The beauty of long-term investing is that we never have to place all of our bets on just one horse.