@vid the big vision is in #ActivityPub the protocol.
I can’t speak to Mastodon’s plans (although it is open source so people can help build it, fork it to be something different, or run custom instances).
You can run many different client front ends that change how you use Mastodon.
And build other types of apps. The “Article” type is for longer posts, and Postmarks is a bookmarking app https://github.com/ckolderup/postmarks
So it’s Twitter and Delicious and Evernote and lots of apps all together.