Considering Schreier's track record, he's likely to be correct. However, in a thread on popular gaming forum ResetEra, Kotaku's Jason Schreier stated that it's not Ghosts 2.
This would be an odd choice when you consider that Ghosts was critically panned due to its lacklustre plot and multiplayer issues. This led to speculation that it could a sequel to 2013's Call of Duty: Ghosts.
While these tweets go back as early as December, the Call of Duty community has just recently noticed them.
The studio's communications manager has been posting a number of images with skulls and ghosts on Twitter. Call of Duty: Black Ops 4 just released in October but that hasn't stopped Call of Duty 2019 studio Infinity Ward from dropping hints on what to expect from the next Call of Duty game.