There was famously an R-rated continuation of the series by The Revenant’s Mark L. Smith that Quentin Tarantino was attached to direct; Fargo and Legion creator Noah Hawley had a script calling for a new cast; and there was the initial Star Trek 4 idea involving time travel and Chris Hemsworth that fell through due to contract issues.
So far, as of last week, we know that Kalinda Vazquez has an idea in development to continue the franchise somehow, and there’s riches of Star Trek projects we’ve heard about over the last couple of years that seem to be moving in slow motion or sitting on a shelf.