Overall, I think as it is now, it should be more considered a final work and it looks great!
I really do like the image, but not for a background sky (like in a movie or anything), because of the radial blur, lens distortion and dispersion (the final composition of the movie it’ll be used in handles that for the whole scene).
Apart from that, you can increase the scale of the sky by reducing star size and increasing them and you could add more cloud coverage of you want, but a lot fainter (the stars don’t usually shine through clouds, unless they are very very thin).
Hope that helps!
Again, it looks really cool as is!