They can just rework kass into an AD scaling champ, I mean most of his damage is melee range anyways. He would be so cool with physical damage instead of magic damage and AD scalings.
Assuming he would build: Shoes- iceborn- hydra- manamune and maybe youmuu+maw or other items
It would allow for his "Filler AAs" to actually be useful
His Q could do more then a light poke and hopefully channel interrupt (Plus would synergize with manamune)
His W's AA reset would be a powerful offense tool
his E would hit hard kinda like talon's but W but slightly weaker but more utility
While his ulti would offer mobility and wouldn't be a ridiculous amount of it since it's range isnt 700 anymore
His entire playstyle wouldn't even be changed much just scale differently thus more valuable builds and not "filler" AAs
So pros:
Same gameplay but actually has AAs
can make better use of manamune
gain more objective taking pressure
Cons:
No hourglass.
I honestly can't say it would be a nerf to make kass an AD champ, it would even open jungle's viability.