Imo Considering Cosmos Part 2 is not wrapped up yet, It could take in a little as month to a few months before something is mentioned. They have to make sure everything is in place, the trailer is done correctly and both movies are packaged together for viewing.
Good thing that fake trailer hasn't gone viral.
Netflix Headquarters is based in America (with locations all over the globe) so all these entities probably need to formulate some kind of order distribution (if they haven't already that is...). If they have already started on all that then a Netflix trailer may be soon but I dont think it would happen while Cosmos is still playing in Japan. I wouldn't mind seeing it in Japanese with subtitles...any foreign film I watch is going to be in the original language with subtitles.
But I'm sure they are going to be doing dubs cause some people hate subtitles.