I see many people clamoring for the death of Facebook but don't they own many of the up-and-coming social networks anyway? If people are ditching Facebook for Instagram you might as well switch to cocaine to stop your crack addiction.
I've tried most of the big ones (except WeChat and other chinese apps, where I don't have a single peer), and I bet on Telegram. They're moving forward with incredible speed, and from all the competitors, they seem to understand their audience and usage patterns best.
Also, it's a platform that's already actively used for commerce. Just like with Bitcoin and darknet, drugs are the primary growth factor (I don't know of any other transactions cryptocurrency is actually used as currency). I expect that after they release their own currency, it will take over all existing crypto from sheer convenience.