Kha'Zix could potentially be changed into a late game assassin if some changes were made

• Allowing the isolation radius to decrease with levels. Currently it is 425 and it could go down to 300 at level 18, or 350 (which is the old isolation radius before it was nerfed to 500).
• "At level 11, towers no longer count as allies for the purposes of denying isolation (I suggested this on another thread)"
• Evolving Void Spikes now allow the heal to scale with X% of Kha'Zix's AD/bonus AD/mana (either that or double the base heal)
• Evolving Void Assault now reduces the cooldown between casts to 1 second, like it used to be before the nerfs.

With those changes, or some of them (I don't know if Kha'Zix could be broken with all of those changes, feel free to discuss), Kha'Zix not only would be a more viable choice for laning, but he would also become a late game assassin. I say this because other assassins can be completely countered and neutered by some factors, for example: Zed by purchasing Zhonya/QSS, LeBlanc by purchasing Banshee's Veil, Katarina with hard CC, Rengar with the fact that he has no reliable escape once he assassinates someone - Kha'Zix would have none of the late game weakness that other assassins have, but he could still be countered by proper positioning.