

All we know is that it will be released March 22nd, 2019. Michael Doughtery and Zach Shields is writing a new script for it--We don't know if any of it is based on Max Borenstein's story treatment. Currently the movie has no director. Rumors have it that Doughtery wants to direct the film, but Legendary is waiting to see how his script looks.
At the 2014 Comic Con producer Thomas Tull said they had procured the rights for Rodan, Mothra and King Ghidorah, all of which are expected in the sequel.
Junkie XL had originally claimed he would be composing music for the sequel, but that was before Gareth Edwards left the project and the movie was moved to 2019. So he's likely not.
The movie was recently and officially titled Godzilla: King of Monsters by Legendary Pictures.
That just about sums it all up...