At the fiscal year results reporting today, Take-Two games backed-up it's profit estimations for the 2019 fiscal year (April 1, 2018 - March 31, 2019), citing Red Dead Redemption 2 and a "highly-anticipated new title from one of 2K’s biggest franchises." The company also stated it will not be showing any products at E3.
The release of Red Dead Redemption 2 makes it unlikely for it to be Grand Theft Auto 6 or Max Payne 4, and I doubt a new Battleborn or Mafia would be highly anticipated. But what about a new Civilization or Borderlands? I'm going to put my money on a new BioShock game.