Grinding Gear Games was planning to release Path of Exile for the PS4 before the end of the year, however, those plans have been pushed back. The new date for the PS4 launch has dropped back into early February 2019. So at least we have a few weeks as far as timeframe goes, and not months. But its still disappointing when a game gets delayed.
Grinding Gear has stated that the Path of Exile delay is due to certification issues. Games need to go through a certification process in order to receive approval for a console launch. That process is a bit different between the various first-party console manufacturers but there are a lot of commonalities.
The statement from Grinding Gear indicates that they still need to get things ready to finish the Sony certification process:
We underestimated the amount of work it would take to finish the certification process during the busy Christmas period. While we hope to have everything ready in January, we feel a lot more comfortable promising early February as a target release window. This will also give us time to work on game performance / framerate, which we feel could be improved before release.
Again, we're very sorry about this. We understand that many PlayStation users were keen to play Betrayal over Christmas and have been eagerly awaiting release date news. We promise that Path of Exile will be awesome on PlayStation 4 when it is released early next year.
It is absolutely worth noting that Grinding Gear hopes to have it ready in January. So, its at least entirely possible the game may hit earlier than expected. Also, since the game is delayed only due to a certification process, fans can be assured the final product is already set to launch.