Entropy. It's why all the kings' horses and all the kings' men couldn't put Humpty Dumpty back together again. It gives us time and makes your hair gray. Everything ends. And that includes Facebook.

Despite what MakeUseOf readers think, it's been predicted that Facebook will shed 80% of its users by 2017 – but which social network will succeed it? Here are some likely candidates.

Tumblr

Tumblr is already immensely popular; maybe not Facebook-popular, but it certainly caters for countless fandoms. If you're a fan of Marvel, Sherlock, Disney, or even Grumpy Cat, Tumblr is the place to be, especially if you're a cosplayer. Founded in 2007 by David Karp, now owned by Yahoo!, the site is mainly used to couple images or GIFs with snippets of text.

David Karp

Could it really take over from Facebook?

Yes. Tumblr is home to more than 174.2 million blogs. Unlike Facebook, you're almost guaranteed to be cheered up. Just search for 'Karl Pilkington' and a smile will spread over your face. And if you think happiness isn't everything – as Karl says, "happiness is like a cake; have too much of it, you get sick of it" – Tumblr is also great for spreading information quickly and concisely. Forget long, rambling press releases: get a great picture, add a paragraph or two and soon, it'll be all over the place.

Reblogging someone's post is easy too, so it's a great way to build up a community and rapport – and that's social networking in a nutshell.

Furthermore, there's a growing number of celebrities on Tumblr including Elf and New Girl star; Zooey Deschanel; Glee's Dianna Agron; and Lady Gaga, epitome of the term, 'Great Divide.'

The Bad and the Ugly

Tumblr can be a very weird place when you initially delve in. You might need to research what 'Shipping' is, for instance. Don't be freaked out to see David Tennant's Tenth Doctor cropped into odd situations. Once you get used to the humour of Tumblr users, it's a much better place to spend those free hours.

Doctor Who Tumblr

Though a large amount of its users are youngsters, it's not always a 'safe' place for under 18s. There's a lot of pornographic content and a copious helping of swearing.

Tumblr cracked down on blogs that advocate self-harm and suicide, but "emphasizes the importance of free expression," which means that NSFW (Not Safe For Work) content won't be banned completely. However, users can enable Safe Mode to alleviate the risk that kids will stumble on something that might raise eyebrows and quite a few questions.

If you're in the UK, the Government-imposed opt-in of adult material on the Internet will probably censor much of Tumblr soon anyway.

If you're just getting started, don't forget to check out our beginner's guide to Tumblr!

Path [No Longer Available]

It feels quite a bit like Facebook, but it's fresher and more streamlined. Dave Morin, co-founder and CEO, is a former Facebook executive, so he knows what he's doing.

Made with iPhones, iPads and Android devices in mind, Path was launched in 2010 by Morin and Napster developer, Shawn Fanning, specialising in photo and message sharing – like most social networks. Even back then, we praised it. It’s more private than Facebook, limiting the amount of friends you can have to 150; it's an unusual stance, but works well.

Could it really take over from Facebook?

Path 3

Facebook's popularity seems to be waning partly because younger people don't want their weekend antics viewed by the growing number of family members on there. Path encourages users to add friends and family, so it'll go the same way as Facebook.

But Path is the best bits of Facebook with added kookiness. You can 'express yourself' with stickers by 'some of your favorite artists' – and no, that doesn't mean Van Gogh, Turner or even Vettriano. They instead indulge in pop culture; sure enough, there's an Adventure Time sticker, as well as Star Trek, Ghostbusters, and – a pleasing inclusion – Peanuts. They'll cost you £1.49 ($2.50), though (unless you upgrade to premium).

It's specifically designed for a youthful generation, and with a surprising amount of funding, it's definitely got a future.

The Bad and the Ugly

Little things might annoy users, specifically its lexicon. Everything is a 'moment' and it encourages you to 'remember life'. It wallows in nostalgia and sentimentality, so if you're not one to don those rose-tinted glasses, Path might not be the right path for you.

Path 4

The real concern, however, is what information Path collates about its users. Two years ago, it was revealed that Path stored its members' phone contacts, though Morin has apologized and the policy changed.

The final problem is one experienced by all new social networks: you can join easily, but good luck finding anyone you know on there. This is likely to change soon, mainly thanks to the fact that Path doesn't suffer from the same envy Facebook does. It's not scared of interacting with other social networks, so you can easily invite your mates to the party.

Zugme [Broken URL Removed]

This young upstart isn't even available for iPhones yet. With a focus on community, Zugme sounds a lot like other social network sites, but it's embraced audio like no other.

Could it really take over from Facebook?

You can add audio blogs and audio comments, so it's designed for people on the go. These days, that's just about everyone. It all depends on how a mass audience embraces audio; are podcasts still that popular? Or are videos the face of the future? You can add videos, of course, but that's hardly different from other networks.

Zugme Blog

Its claims of unconventionality may draw people in, as well as its offer of free ad space:

"We want our users to reach as big of an audience as possible and promote themselves in really unique and exciting ways. Giving users ad space in exchange for traffic is a win-win situation," says Zugme representative Sean Kelly. "Our ad space program really gives Zugme users the opportunity to promote whatever they're passionate about and create an invaluable amount of exposure."

But best of all, it's perfect for musicians, allowing them to tag and search specific music types and cities. It's Facebook for the American Idol/X Factor generation.

The Bad and the Ugly

Zugme needs a lot of refinement; launched only last year, it's still finding its identity. It tries to combine business with social media — something that might work for smaller companies, particularly freelancers, but at the moment, it sits uneasily between LinkedIn and Facebook. You can't offer everything for free forever, so we've yet to see its full business plan.

The network's biggest crime is its ugly Android interface; plain and clumpy, a sheer white face dotted with simple boxes containing videos and brief bits of text. But then, it does exactly what it says on the tin. It all depends on what you want from your social network.

Conclusion

There are, naturally, many social networks out there, vying to compete with Facebook and draw in its dwindling users. Tumblr is ready now and Path imminently. Zugme might need a little while to establish itself, but there's plenty of time for that.

Unless, of course, there's a sudden interest in MySpace again...

Who does your vote go for? Is there a social network out there that has a chance over Facebook?