Had an awesome thought, which I'm sure others have thought of as well. What if a game mode was created where instead of a max of 6 items, there was NO limit? Or at least a limit of 10 or something. That way there's no "falling off late game" for some champs, and the fed get more fed. I just think it would lead to so many fun changes!!
Imagine 
with 10 
!!!!!!
= 8000 bonus HP + 240 hp/5
THE POSSIBILITIES ARE ENDLESS!
While yes the "possibilities are endless", there are a few things that I think you would want to adjust and I'll start with why rather than how:
How many games have you played where everyone in the game has gotten to full items? I've played maybe 2k games, I've personally been full build before the game ends maybe a hundred times. Only time I've ever done it as support was when I was messing around as velkoz or someone and ksing (er I mean... securing... look its hard to turn the giant laser off because its all your dps late game team fights) everything humanly possible.
"The fed get more fed" well, I guess it'd be easier to call that "the fed have no limit to how fed they can get". Money earning changes would have to be made for the mode, and since it'd be available to everyone: I'd probably suggest something like lowering kill gold (150-200 would be fine) and raising gp10 (fairly significantly, more than you get on aram map) mostly because one fed member can still end the game before people are approaching past six item.
Since turrets these days are like cheese to every champions flamethrower, if you wanted to extend the game as I imagine is your goal, would probably want to increase turret armor or health or something.
Frankly not entirely sure how to make an idea like this work, though it's creative to think of and work with. Maybe someday they'll add it.
Let the "unique" abilities stack as well.
