I mean, Caitlyn needs nerfs for being one of the best ADCs in every situation (plus a really high Pick/Ban rate in Pro play). Draven needs nerfs for auto-winning lane phase with a Vamp Scepter + his Q, and then auto-snowballing with his passive. And once those are out of the way, Twitch will be the top ADC, with no one to keep him down in the laning phase. So then he will certainly need nerfs too.
But eh, if all that happens, then someone else (probably MF, Tristana, and Kog'Maw) will just take their place. And relative to other points in recent League history, the current ADC balance is actually pretty decent. Cait, Draven, and Twitch may be clear front runners, but 10 bans makes them managable, and below them there are like 10 other viable ADCs. The only truly unviable ADCs are Corki and Ezreal (and people still play plenty of Ezreal).
So overall, I think I can wait for ADC nerfs. I would be happy to see some nerfs if they are done right, but I'm in no rush to see some other ADCs take the OP crown.