Rockstar confirmed development
While Rockstar has confirmed the game is in development, communication about it is still very cautious, and that is completely understandable given RDR2's chaotic development. Keep in mind that employees were overworked, and a huge backlash erupted during that stressful pre-launch period. As a result, Rockstar seems to be betting on a careful strategy to avoid a repeat, and you can bet they won't communicate too early about the release to avoid getting cornered and having to push the dev team again to ship on time.
Rockstar is taking its time, and we can't really complain. More time also means more work on the game and better attention to detail, and we can only hope it will be enough to fix some of the issues that surface today with RDR2, where online is nearly abandoned by Rockstar, which strongly annoys players, or with GTA Online and its endless loading times and disastrous server management.
So while we know from official sources that the game is in development, we really don't know when we'll get to play it. You can read our article on the Red Dead Redemption 3 release date for our take on the matter.