Finally! I’ve been saying this for years to whoever will listen. Craig Hockenberry saw the light:
Federation exposes a lot of different data sources that you’d want to follow. Not all of these sources will be Mastodon instances: you may want to stay up-to-date with someone’s Micro.blog, or maybe another person’s Tumblr, or someone else’s photo feed. There are many apps and servers for you to choose from.
It feels like the time is right for a truly universal timeline.