Quite a few people I know ranging in age from 20s to 40s do. There isn't really a replacement with its defining characteristics:
- One-to-many blog-like posts
- Mostly for interactions between people who actually know each other
- Most people have an account and at least occasionally check it
It's that last point nothing else can match. If I post something to Facebook, most people I know have a chance of seeing it. Five people I actually know follow me on Mastodon.