GTA V is one of the most successful and successful games of all time, and Rockstar, of course, will not stop there. However, with all the work involved in producing Red Dead Redemption 2, it was not expected that the studio would get going on GTA 6 anytime soon - and that seems to be the case.
Actor who specializes in working for motion studios, has included at least one capture section dedicated to the GTA 6 game. He also says he has worked on the same task for Rockstar during his career. Development of Red Dead Redemption 2, which has already been confirmed and has next release.
It is worth remembering that last year a report suggested that the studio had begun the "preliminary work" of GTA 6. It is possible that the project, by then, is already advanced enough to begin capturing motion to apply to the game.
Another equally reasonable explanation is that Neff may have been told that his work would be used in GTA 6 when it might be for a different game. This practice is common for studios just to dribble leaks.