People need everything in one place so they move to social media. They really don't care for small forums and what they need is something popular so they can act.
Socia Media is officially on the climb, a forum I was a member of has since moved to the world of facebook group. - tougher to moderate and make unique to be honest with you. I'd love to stick with the forums.
I wouldn't say take over, but sites like facebook, discord and others have without a doubt hurt forums. I know its kind of hard opening up a forum compared to a discord channel these days.
I think there will always be a userbase for a traditional forum. Not everyone likes Twitter or facebook, but wants a more trusted source with their data. (I know that's laughable to say but it's true)
Forum Authority is a general discussion forum. We currently have a variety of categories to choose from, where you can participate in discussions. We also have many features such as a powerful credits & awards system, custom upgrades, plugins + more! Here you have the opportunity to meet new people, learn something new, find unique resources & tutorials, win contests & prizes, receive freebies and be given advice or help.