Gene Kelly's work as an actor has been limited in blu ray to Singin' In The Rain and the limited edition Cover Girl.
Also An American in Paris, which was the first Kelly film to be released on blu-ray.
What's holding up most of the Astair/Rogers films is likely the RKO elements which relatively need more time and effort to fully restore than the Warner Brothers films and most of the MGM titles. We'll probably see more of the color Astair films in the future. However, it seems WB is being a bit too selective on what it releases on blu-ray, generally limiting new releases to the perennial classics. Hopefully, we see more in the near future.