What if Kha's W auto-aimed on isolated targets ?
Kha'Zix is way behind every 1v1 champion and far from Rengar. While Rengar can burst down any squishy in a second and run away, Kha'Zix can barely do anything in teamfights and rarely something in 1v1 in this meta while his gameplay implies that he should burst down isolated target.
My cure to that would be to make Kha'Zix "rockets" like Urgot's Q. Basically, if a target is isolated and locked on, all W projectiles should auto aim on that target and deal bonus damage. It would even fit the skins like the Mecha one where the isolation is a huge "LOCK-ON" icon and you shoot rockets !
Also, make his ult stack with time or something else because it's easy to waste and isn't as efficient as Ahri's ult to make it worth the one use and 1/2 thrown away.