I think the new Vayne Q nerf is meant to allow her enemies to bully her even harder early on

If you think about it, with Vayne's Q being super-weak early, she will simply have worse early damage, further exacerbating her early-game vulnerability against equal-skill opponents. This means that if she's getting bullied, if she tries to fight back, she'll get stomped on and laughed at.

So when Vayne does get that Q nerf, attack her more often early-game, and you may notice that you simply outpower her in early fights.

#"But it's her late game!"

No. Here is the thing about Vayne. Did you let her reach her late-game? Then you deserve to get your ass handed to you by her. Pressuring Vayne is not limited to the laning phase, but when you're roaming too, you want to make her a constant target.

This nerf makes it easier for you to pressure Vayne early, and is not meant to diminish her late-game power because that's what she's meant for. Try making a comp that can kill her team in 25 minutes rather than dragging the game out.

My 2 cents.