Tbh, Kassadin is still very strong.

And why is he still the champion with the lowest winrates? ( be laughing at a corner...)

I played a couple of Kassadin top lane games, and gotten pretty good scores with him, some with suchs like 5/0 & 7/2, I think, just roughly round there. I don't get why a simple ult range nerf would scare the bejesus out of everyone.