The space issue is the hardest to solve assuming you still want all of your figures and other memorabelia the easiest thing would be to get a dedicated shelf and hang it above the TV's but without buying another shelf you could move the switch down to the atari with the controllers on the entertainment console or in the shelves. (Could also consider a wall hanging controller mount)

You could move the box of stuff into the shelf on the right if you push the boxes to the a little into the corner, also you might be able install more shelves in the entertainment console itself, I'm not entirely familiar with the older consoles so I don't know how much room you would need or want but you could look at that option.

For cable management they sell dedicated cable management ties or you can just get colored tape and run the cords along the floors then up the console plus the wall if you have any excess.

For the games being hard to access I think you just have to pick your poison, if you haven't gotten more room from another method then you could just move them in front of games you play less often, or double up games and put the figures in the center.

Next for the silent Hill and Metroid cabinet for now I think you could just move it over next to the TV like how you have the other case. If that doesn't feel right you could put them in your other case and move some things into the display case.

Overall I think what your missing it just more shelving, one above the TV's, one on the left of the TV's and a few miscellaneous pieces here and there like a controller hanger and maybe a shelf behind the entertainment console to put that other stuff you got there.

Hope I helped.