Twitter faces no real threat from Mastodon until they streamline their sign up process and mask the "decentralized server" nonsense. I understand that the people here don't see it as nonsense, but the millions of less tech savvy users needed to make it a true Twitter alternative do see it that way and it will prevent Mastodon from ever being more than a niche service. It's a baffling process to the everyday user who has signed up for dozens of different services over the years with a simple email and password (if not single sign on).