The internet is going away, this just takes time. Just like when forums and IRC died. Because the internet exist, its still online but those platforms are dead and gone in reality. When the internet goes, they go. Social media is going to be long dead by that time and its already starting. It takes time for 5,3 billion people to get off the internet. There are around 5 billion users that use some type of social media. This takes time to end.
In 2005 there where around 1 billion people online. It took 18 years to add 4,3 billion people online. It is going to take at least that long, if not double that time for people to stop using the internet (as long there is not a major global disaster or war that might change this path).
The internet and social media is going to exist for a while longer, both are dying and going away. Its just going to take some time.