While nothing official has been announced yet, the Korean ratings board has proven a reliable source for outing this type of thing in the past. Plus, with Syphon Filter and Syphon Filter 2 already available on PS Plus Classics, there’s no reason why the third game shouldn’t also get the same treatment.
Syphon Filter was developed by Sony Bend Studio and was released for the PSOne on November 6, 2001 in the US and in Europe on November 30.
Now, how about a brand new Syphon Filter game, eh Sony? We can live in hope!