Depends on what ways the industry will innovate.

Until we completely exhaust out every idea possible, we won't be stopping anytime soon.

Yes, we will reach a limit in 10-20 years imo.

No, we'll break though that wall once new forms of computing take off.

Yes, but once technology is advanced enough, it will be overcome.. happens a lot with technology now

It will likely take more than half a century in the games I'm interested in, (RvR MMORPGs);

Namely, some modern (or even in development) large scale PvP games still look worse, or even much worse, than for example Lineage 2; And that's nowhere close to a standard today.

we allready hit the wall to be honest. There isnt enough manpower and money to make games look even better. Artstyle can only play an important role now

Have you played games on a high end PC?  Games like driveclub have a mediocre framerate.  Still pictures won't be improve much, but consoles have much more room for improvement.  Increased framerate.  More dynamic backgrounds.   Better shadows and lighting.  Better aliasing.  etc. 

Even PC games have much more to improve.  More lively world with numerous NPCs and dynamic backgrounds.

We've hit the wall on how good the visuals look.

Graphically, of course. You can already see development shift from pure graphics to more advanced AI, VR (not that VR is gonna take off), and bells and whistles rather than focus on 1080/60. Next gen all we'll see differently is that it'll be a consistent 1080/60 and maybe 4k/30 for consoles. Not only is it becoming physically impossible to advance much further than we are at, it's also never going to be cost-effective for the large majority of developers to try anything above 1080/60.

Yeah i have.  My eyes can't tell the difference between 30 and 60FPS.  It's reached the limit for me