I have asked myself the same question - who will replace facebook as the next social media giant? They have definitely lost popularity due to everyone being on there now (you don't really want to share everything with your grandma and your uncle do you...). But also, facebook instagram and whatsapp are in a crisis because of the privacy settings. They are all one group as we know, and many users are scared and don't know what will happen to their date.
Decentralized cryptocurrency is definitely the way to go, thanks for this list there were a few on here I didn't know yet. It will be interesting to see how these develop in the future !