This is the best way I figure I can pitch this idea for Rebecca sugar and men in black movie owners to make another sequel. This is my pitch however if we can get another men in black sequel , and they work on it together let them have free reign. Steven universe is in new York city, willfully unaware of the world beyond beach city and the gems. he gets murdered , men in black must return his gem to beach city, or his body. 1. he is alive , 2. his gem becomes a new entity when reformed beyond Steven or pink diamond, but a pink diamond. 

this could be a quiet opening for a new movie or 10-20 minutes long.

new agent learning about the great diamond authority and what Steven is and his importance to the universe.