If they toned down his Q's evolution, to be more ratio and less base, then I'd say that'd be fine. The entire issue with Kha'Zix has been that he does damage without going damage. He'll 100-0 some one who's isolated with only a couple damage items, which has made things a bit silly since it punishes Bronzies while Gold+, Zix is almost useless since his damage is put into that isolated Q that's been nerfed in damage a few times, plus the isolation range increase, and his R got the 2s delay (It was added because of the old 50% damage reduc, which was removed not long after the 2s delay was put in).
He's just been boned so hard since release. First, he was poking too hard with his W and doing nothing but poking with evolved W as well as doing a ton of burst mid-jump by pressing W+Q mid-air, so his W can't be used mid-jump anymore. Overall, his W doesn't do much, they nerfed Zix's E hard, and his Q only does a lot if the person is isolated, but the isolation range is the equivalent of Evelynn's passive...
Now, I would more say tone the isolation range down and nerf the damage slightly, that way he can do a lot and take advantage of people not grouped, plus he could then be paired with champs like Amumu, Malph, Sej, and the like who make you want to be spread out. He'd have a great place again. Right now, he's just one of the best Dragon/Baron stealers by doing a 1k Q plus a smite. His Q has a 221 base isolation plus 180 with evolved Q and a 156% base isolation, with a 104% bonus from evolved, meaning he does 260% of his bonus AD on top of 401 base. With 200 bonus AD (All of two or three items, really) and he's doing 401 base plus 520, so 921. He can nearly outsmite a damn Nunu and that's a scary thought, but the problem with that is, that damage is reduced to 170+120% of his bonus AD when not isolated. So in most team fights, he's doing 170+240 every Q. It's on a 3.5s CD, but when you're supposed to burst some one, doing 510 damage on a 2k health squishy plus 400 from W (200 base plus 100% bonus AD which is 200) and 245 from E (205 base plus 20% bonus AD). That's all of 1155. If you AA, you can do another 300 from your AA and 190 from your passive, which totals 1645. That's if the person has absolutely no armor, which... isn't going to happen. Base armor is about 50 for ADC's. Unless you're stacking 19 ArP from runes, a Ghostblade, and a LW, you're not ignoring the 50. With just the LW, you've still got 30 armor, which totals about 23% reduction. We'll say they didn't get MR or armor in runes just to make our damage look bigger. There will be 30 MR base on an ADC/APC, so we can use the 23% on the total and ignore the passive doing magic. That means you'll do 1266 damage in a single combo.
I dunno about you guys, but 1266 is pretty fricken tiny. Zed's double Q and E can total 352 base (117 on second, 235 on first) plus 150% of bonus AD from the Q and 180 base plus 80% bonus. That's from a range and with the same items, that totals 532 plus 460 (230% bonus AD of 200 AD), which is 992, without a mana cost... without having to jump on them. Now, if he does jump on them he can add another 300 AD into that for a 1292 total. If he BotRK's them, that's 200 more damage, meaning his AA would've proc'd the 8% max health as well to do another 160, meaning he'd do 1652 damage without even pressing R. Zix does 1645 with a full combo. Zed is considered 'healthy'. Zix is considered useless outside of Silver and Bronze. x.x
