This request is still on the backlog.
Teams is already threaded! Just make sure to use the “Reply” button instead of the bottom compose bar when responding to someone’s previous post. That will thread the conversation.
Thank you for your continued feedback. The feature team is actively working on this feature as well as doing work to give users the choice to open Word/Excel/PowerPoint files by default in Browser, Office app or inside the Teams app. We will share an update here as soon as one is available.