True Random All Mid
A game mode I was thinking about would be a true Random aram game mode. Each person has a chance of getting any champion unlocked or on rotation, but their options are not limited by what every other player got.
Basically, both sides could have a Ziggs, or your team could have three Garens, or any combination possible.
Another option would be a blind pick where your team could pick any number of a single champion, but not be forced to have all 5 be the same (all for one), so you could have two Yasuos and three Alistars if your team wanted to.
Of course, this will likely never happen, but it is fun to throw ideas out there!