RSS was there before Facebook and Twitter.
RSS will be there after Facebook and Twitter.
One of the neat things about RSS is that I don't have to care whether it's the Most Popular Thing. I just need a reader, and someone publishing it. No "boil the ocean" required. I used RSS back when the number of publishers could be counted in the dozens. It was still a useful technology!
If you're then inclined to argue "but what if everyone stops publishing it?", a "boil the ocean" of its own, my response is that I'll worry about that when it happens. That would take a lot of people to stop publishing it, and... in modern times, it's so easy to publish RSS, and you own it, not like your Twitter or Facebook integration, so I don't expect the value proposition to go sour for everyone for a long time. (And I don't really have to worry about all the readers going belly up, there's enough open-source desktop readers if nothing else. To say nothing of the open source server-delpoyable ones.)