I believe that, just like RSS feeds did not become mainstream while Reddit did, the current state of the fediverse will not gain mainstream popularity; however, it'll serve as a stepping stone towards a new federated internet that'll be seamless and intuitive for non-technically-inclined individuals and those who are indifferent to the implications for privacy and digital freedom.
A tool that uploads and updates videos across multiple platforms while syncing descriptions, tags, etc is something that would be incredibly handy for creators while also being something that PeerTube could piggyback off of. "Why not upload my video to another platform I've never heard of? It can only lead to more exposure."