According to Deadline, Legendary is moving Kong: Skull Island from Universal to Warner Brothers "to unite the property with Legendary’s other giant franchise, Godzilla."
They're reporting that a Godzilla versus King Kong movie will go into production after Gareth Edwards' Godzilla sequel is released in 2018. They added, "I’m told this is happening very quickly with moves going all the way to Japan, where Godzilla rights holder Toho is based."
Kong: Skull Island will be released on March 10, 2017 and Godzilla 2 will be released on Jun 8, 2018.