Widowmaker is an infinite skill-ceiling hero. She has nothing that will ever force a player to put on the breaks as their skill increases, and this doesn’t address that problem.
Here is what this change is going to do:
In low ranks you’re going to hate having a widow on your team even more because chances are greatly against them being any good.
In low ranks you’re going to love having a widow on the other team because chances are they suck and the game will, in effect, be 6v5 until they swap.
In average ranks you’re going to love most of the enemy widowmakers you see, and hate most of the friendly widowmakers you meet. However you’re going to occasionally detest the enemy widowmaker who can actually land shots, and the friendly widow carries will hardly be noticed (because you won’t believe them, for the most part).
In the high ranks nothing of note will change. You just won’t regularly see good widowmakers for another 50-200 SR.
She needs a skill ceiling and/or better counter-play. This gives neither.