Even with rapidly evolving technology the difference in graphics won't be as noticeable as it was from PS3 to ps4.
Even if you quadrupled the power of ps4, the difference in graphics wouldn't warrant spending $400 on a new console.
English
-
It's not just about graphics, I think the biggest leap graphic wise would've been from ps2 to ps3, it all comes down to the system hardware and processing power which will mean bigger maps/world's, less load times and the more things on screen at a time