Open Lanes
I'm sure everyone remembers the mage bot meta, yeah? Well at least in theory I don't think it's a bad idea. Having more picks available in the lane can't be a bad thing. I think the issue was more that ADC at the time was so garbage that dps mages like Cassiopeia etc. did a better job of dishing consistent damage than the marksmen who used to populate the lane.
Now that ADC is a functional role again, at least for the most part, I'd like to pose the concept of 'carry' lanes as opposed to bot and mid necessarily being separate champion pools.
That being said, actually implementing something like that sounds like it takes a whole lot more game design know-how than I have, so may as well ask the community if or how that would actually be possible.