Permanent Flash - Rotating Game Mode Idea

With League being balanced around the usage of to the point where it's required on nearly every champion sans a few in specific niches, what if there was a rotating gamemode introduced that allowed players to have flash as a standard, and take another summoner spell into battle. It has been said (at least to my memory) that the reason they haven't done this is due to the fact that the game is already in a pretty good spot despite 's dominace, but as a rotating game-mode Riot would be able to collect a lot of data on weather or not it's a good idea to make it a staple spell, or finally prove it wrong to those who say that making it a staple spell would be a bad idea.

Adding it through a rotating gamemode allows it to not disrupt the base game in any way, and creates an environment where new strategies can be found out.

Thoughts?

(also i didn't really know which board to put this in so i chose the one that seemed to make the most sense, sorry if this is the wrong place)