I hate the premise of this, mostly because I can barely figure out what I'll update my Facebook status with next week, to say nothing of two and a half years from now -- to also say nothing of how any of you people handle your own personal Facebook situations.
What is comes down to for me is this: I have very little faith in the improvement of the human race. So I suspect that the Facebook of 2017 will be much like it is now: political arguments and human drama balancedout by distracting and soothing pictures of babies and animals, punctuated by the occasional hilarious or poignant video.
There will be wars and disasters in various parts of the world, some we will try to raise money for and others we will try to ignore. Some people will hate the president and others will love the president, and other people will just scroll by those posts as quickly as possible in order to get to the next batch of adorable baby/animal pictures. Some people will bitterly comment on friends-only posts about how much they hate all the photos of babies and animals and weddings because they're not in the same boat. Others will beg their friends to post more photos of their kids because sometimes those photos are the only hope we have in the future. Fights and love-fests will break out side-by-side, and you will still wonder why that random person unfriended you despite your Facebook presence being nothing short of amazing on a regular basis.
Facebook will probably remain a good place to keep up with corporations or brands (okay, and family members too, but clearly that's not the point), and some people will probably still be playing Farmville. Or is it Hay Day now? Maybe it'll be ZOOOMG and you will stil have that one aunt who consistently asks you to help clean out her lion cages. (That's how those games work, right? I somehow managed to avoid them against all odds.) Either way. Most likely a number of us will continue to use Facebook the same way we always have, unless Google has managed to take over our lives completely and made Google+ a reasonable alternative.
My ultimate hope for the future, all else be damned, is that by 2017 we will live in a world where people stop sharing Onion articles and believing them to be true. It's unlikely, but sometimes I like to put faith in the impossible.