Composer Gustavo Santaolalla hinted that The Last of Us Part II may be released in 2019 during an interview. He gave this interview for an Argentinian radio station.
Robin Gaming made a video about this
The composer stated that the work on the game should be done by 2019 but a release date can’t be set at this point. The development on The Last of Us 2 began in 2014, but wasn’t officially confirmed by Naughty Dog until 2016.
Here is the part where the composer mentioned the release date.