Kassadin - Rift Walk needs the range back to 700

With League of Mobility being an increasing thing with every new champion it is harder for Kassadin to do what he is based around - chasing people down relentlessly. When Rift Walk was changed to 500 range the mana cost and cooldown were reduced drastically as well as adding some small damage buffs to it but it also meant that he could not even get from the front of a minion wave to the back in a single cast. For an assassin of his calibre and scaling I understand it was a problem in the past and would still be problematic to a degree.

Riot is fine with infinitely scaling Nasus and Veigar and how they become very dangerous late game. Neither of those champions have the mobility of Kassadin but they also have far greater base damages. In fact Kassadin does not have a single ability with a base damage higher than 180 at rank 5. I have issues with both of these but I do not have solutions that anyone would consider useful. I just want Riot to admit that they basically nuked Kassadin from "permanently banned" to "not worth playing" and either offer some insight into why he has been left in that state or possibly some adjustments.

I won't pretend that it's easy balancing him because of his chase potential but it seems like as long as he isn't a permanent feature on the ban list Riot don't care. I just know that if any other champion was hit so hard they went from must pick or ban to rarely seen anywhere they would be buffed or changed enough that they were more balanced than just plain gutted.