my pc vs ps4?

It's hard to say. Probably 5-ish years until it's down to low settings, but that could change depending on various factors.

Keep in mind, after about 6 years, the PS3 and 360 started running games below PC minimum settings. Crysis 3 and Metro LL on the consoles, for example, ran at about 600p, 24 fps, below PC minimum.
 


Yeah. I had a 768MB GTX 460 until recently, and it'd still put everything new on medium. Less impressive new games on high/ultra.
3 years would be too short. I'd guess at least 4 years. As you can see in my reply, I'm guessing 5 years if he's okay with 1080p/30+ fps.