according to various analysis I have seen, the ps3 when launched reallly was matching high end pc hardware, the ps4 isnt. If watchdog runs the same on a ps4 as a high end pc, then the high end pc isnt been stressed. Its like when I loaded up dark souls2 on my rig (which is only mid range spec), I have never seen my gpu so cool and idle during a game, it has almost idle temps and doesnt even run at full cloks as the game has the gpu barely strolling.
With that said tho, the game only needs to look "good enough" and gamers sume as time2die who like visuals are satisfied with watchdog so it does look "good enough" and the ps4 can cope with that.
What has me going along that this game needs next gen consoles is the fact on previous gen, npcs and cars are removed, which reduces the immersity of the game.
So as things stand if I buy this game I think it will be for pc.