I guess I can follow people that post about the topic and keep up with a part of the discussion but what if someone I don't follow or someone new has something interesting to say??
@freemo @kosame Yuo will see posts by other users in a thread discussion, and maybe get interested in their posts; visiting their profile is the next step for me.
We also see a lot of new people via Boosts in our Home feeds. Your followed accounts posts, as well as any boosts they create, will show up there.
I do miss a more formal, focused, Forum like structure, but here it is the way it is.
We will have Bookmarks in upcoming versions of Mastodon, some forked modded versions already have them (Glitchsoc being a particularly interesting one.)
@kosame Topics are followed via hashtags usually.