Give Ahri the Thresh treatment

Not balanced in the slightest, we have already seen you shitpost once, quit doing it already

Edit: for those of you wondering what else he has been up to https://boards.na.leagueoflegends.com/en/c/gameplay-balance/Ws7E2y7w-how-to-fix-ahri? Here you go

the idea is nice, doubling the CD isn't however

How about no. The reason Thresh's Q deserved it was because it's a hook. It's a CC that drags and would setup your team/the rest of his combo. If anything her Charm would be the candidate for this treatment, but even then double cooldown is to much. Increase it by some seconds and drop some of the cooldown on hit.
Ahri's Q is a forward and back, slow and dodgeable skillshot that deals a little damage on the way out and any of its good damage on the way back in. No CC of any kind is attached to it to help your team.