It's true. The Kha'Zix changes, while admittedly interesting, are just going to bring him back to being a utility based gang spammer with no interesting interactions.
The problem that Riot has with Kha'Zix is that, for some reason, they think that isolation works well with their "do 50% of their HP, ult and then do it again" idea for Kha'Zix.
I'm sorry, but that's never going to be okay. Assassins one shot. That's what they do. Kha'Zix relies on isolation. If he uses that to do half their HP and then ults to wait out his admittedly short CDs with the intent of finishing them off, do you know what they're doing?
Leaving isolation.
Now there's little to no kill potential. If the objective of this "assassin update" is to make Kha'Zix a fighter, someone should just say it so we can stop beating around the bush. That evolved W spam gank jungle garbage was less healthy than evolved W passive proc mid lane Season 3 nonsense. It wasn't interesting and it wasn't Kha'Zix. That's why it got changed.
Now what? With his assassination potential gone and an absurd amount of spammable CC, he's going to be the same thing he was during S4 (?).
If they think that Kha'Zix's burst is too high, fine. Nerf it a little and make up for it with the passive changes. Good, we're done. No need to buff W to make it the obvious go to flavour of the month choice.
Maybe I'm being naive, but it seems to me like this whole assassin update came about (like the Maw nerfs) because of Zed. Zed is always at the core of all assassin events (as with Duskblade). Nine times out of ten, when someone is complaining about "AD assassin mids", it's Zed.
Not saying Talon, Rengar, Shaco, and LeBlanc didn't need reworks, but come on... it was Zed guys, let's just accept that. It's always Zed.