There is 3 major points to consider about the rework that is most definately going to change her optimal gameplay. her q no longer critting is going to make it way less useful to focus down squishies in fights as her. Her w scaling lower early and the same late will lead to people w maxing instead of q maxing. Her ultimate change is going to add alot of counterplay to her.
Looking into this more indepth, when vayne w maxes, it is HELLA more optimal to rush a bork than a ie/shiv. Coupled with the fact that her q cant crit is actually just going to cripple the crit build. Her viable build is going to be bork into 2 atkspeed items probably. Guinsoos might become meta on her now that her q cant crit.
Even deeper into this her ultimate is going to be stronger but weaker too. She Is going to have the potential for a longer duration, HOWEVER, it also has the potential for a shorter duration. If she cant kill her target in 8 seconds (down from 12-15 depending on rank) its just done with. So her targets can just flash away and her ults gone.
This rework is going to turn vayne into a pure tank buster, as she was ment to be. I love it.