Substack is launching the ability for writers to paywall their entire Chat or specific threads to paid or founding members only.Paywalled Chats will help keep conversations intimate and troll-free, while also acting as a paid perk for readers.Substack is upgrading the Chat interface to improve navigation, searchability, and real-time updates.Substack sees Chat as a viable alternative to Twitter and has introduced other features like 'Notes' to compete with the platform.