I like the Vi nerfs Riot, I have a suggestion to look at if Vi's state seems healthy after a while.
I like how you specifically reduced her ganking pressure while keeping her lategame/laning power for more versatility with the champion.
If it is possible, when Vi's popularity goes down; give her a small bonus AD ratio on Q or R to stand up to her "Assassin" tag in the shop, to give lane Vi a reason to be played.
Thank you for 5.5 patch by the way, best patch in forever. :)