The Discover timeline has evolved and will continue to evolve with the community. The guidelines will evolve too. We want to have additional curators from the community. We need to build some tools to make that possible. It would be particularly nice to have curators who can encourage discussions and connections in languages other than English.
In the linked post she lays out how Discover is curated. It is nice this is now transparent. See also their Micro Monday wherein they answer a question from me re: this as well.