Draven can last for a long long time beyond early game. It's not very accurate to say he's the leblanc of adc (and pretty sure everyone agrees that you can't do much to stop a leblanc's damage midgame beyond wait it out so that she falls off naturally.)
If there's any adc who got no scale late game, it's probably Cait. She has no CC/Initiate (Ashe's niche) but has no steroids of any sort to last later on. All that she got is to bully early game with her range. She's totally viable, just that she's the opposite of vayne: no early game, beast mode late game.
Jungle changes will affect what junglers are viable though, which in turn affects everyone. Right now Junglers are all cc machines and won't get much damage items. Supposedly riot's new changes will "fix" this.