Hugh Jackman is now way too old to play Joe Gillis in a movie or TV version of SUNSET BLVD. -- unless they use CGI to youthen his face throughout the entire film, which I suppose is possible.
I very much doubt we're going to see a film of this musical, but if one is announced with Glenn Close to star, they would probably have to use the original cast recording for her vocals. Seriously. (There were strong rumors that at least some of her vocal performance in the recent Broadway revival was pre-recorded.)