I have quite some PS4 exclusives on my shelves that were meant to be only on playstation. They even have this mark "Only On Playstation" written on the box. Yet I see most of them in platforms like Steam and GOG these days. Some aren't even too old like Horizon Zero Dawn or Metal Gear Solid. A few titles might remain exclusives like God of War I guess. But most of the exclusives have been ported already and they still continue to port even more. I bet this won't change because it's not like they've stopped porting to other platforms.