I'm so sad that Gragas 
may be getting nerfed from this. His ult offers so much utility, whether it be intitiating or disengaging fights. That with the cc in his kit makes him strong. His early game is stronger than most tank junglers which is why I think he's a favorable pick. But as it stands right now, if he gets nerfed, he will become so much weaker in top or middle lane, where he is already weak in. (his laning was gutted when they reduced damage to his Q on minions)
I understand that Riot wanted Gragas to be a tanky in your face brawler, but he would get bullied out harder than before in lane if he gets nerfed.
I honestly thought he was going to become a support pick when they recently buffed his Q slow and gave him more mana at level 1. But after Cinderhulk became the jungle item for tanks, he found a home in the jungle.
I don't know how they will nerf Gragas if they do, but I honestly think he's in a healthy spot right now. His damage is relatively low, particularly in the late game. (his W is single target and it is the only damage source that scales into the lategame) So he really only provides utility in his CC and and displacement on top of his tankiness.
Sejuani is definitely first in line of the tank junglers to be getting a nerf, she has damage on top of her CC and tankiness. She also has an ability that scales off of her max HP, making her one of the biggest abusers of Cinderhulk. They have already nerfed her once by reducing the slow on her "missed" ult (it was a tad ridiculous), but they still need to reduce her damage a bit before she can be in a healthier spot. Probably reduce the scaling on her max health for her W.
Cinderhulk could probably be nerfed a little bit as well. Possibly they could reduce the damage it outputs to champions or just bring it to a point where it wouldn't outclass Sunfire Cape. This could help reduce toplane smite Shyvanna that people complain about a lot. (I don't mind this at all, or really cinderhulk in general but I imagine nerfs will happen eventually if tank junglers keep crowding out other junglers).
Bottom line. If Gragas gets nerfed, I just hope it's a small one. He's been my favorite champion since his rework and I am glad that he is seeing competitive play (particularly his tanky build). His build options are very diverse as he can be played as a tanky brawler or a mid range mage or somewhere in the middle and he can still be relevant. He has so much utility that he can be played in a variety of positions (Top, Mid, Jungle, and Support) and has multiple playstyles. Gragas's Ult can be gamechanging but it can also mean the death of your team if you use it incorrectly. He is sitting at a high winrate currently, which is why I think he will be eventually looked at as a problem, but I hope they just revert the slow increase on his Q as I thought that was a bit unnecessary. If he continues to be a problem after that, they may have to increase his CD's somewhere.
Lastly, I apologize that this isn't exactly what the OP was discussing. But I do agree with what he said about buffing X and nerfing Y. I think that is what happened. They nerfed all of the fighter junglers (besides Lee, lol), and had been giving buffs to Tank junglers (Gragas wasn't seen much as a jungler before this; he was seen more of a Meta Top or Middle laner) before the release of Cinderhulk (which was a huge buff to ALL tank junglers). Cinderhulk accompanied buffs to other tank junglers (though Volibear and Zac see far less play), and then we saw Sejuani reign supreme over every other jungler until she became a 60% ban. Pros then looked to find the "discount Sejuani" and in that they found Gragas, who honestly has a similar playstyle. Gragas became FotM and now he sees a high ban and pick rate with a 50%+ winrate across all tiers of play. Now we are looking at a buff to fighters in the new Black Cleaver and players are calling for tank jungler/cinderhulk nerfs. I'm afraid that Riot will overdo it a little bit when figthers/bruisers get a few more buffs and they nerf the tanks a patch or two later. I read something about the balance team waiting out this current meta a little bit to see what happens as people adjust before they make changes. It will be interesting to see what happens in the next few patches after 5.8.
To the OP, I'm glad you are having fun with Kha'zix as I think he is one of the champions who needs a buff soon (something small) to bring him back into the realms of viability outside of Yolo-queue. And I think Nocturne is going to become a stronger pick in the near future. He has been seeing little buffs here and there, and I think one little thing is going to push him into a contested pick, so keep at it.
If you actually read this entire post, thank you. I ramble a lot on these boards and sometimes, my posts go pretty long. I hope everyone can see where I'm coming from (we've all had that favorite champion that sees competitive and then gets nerfed). I like that they added Cinderhulk as it did give tank junglers strength in the game. I really don't mind that Shyvanna takes smite toplane sometimes. I hope that Riot reverts some of the changes they made to fighters in recent patches to bring them back into their roles as early game junglers. Rek'sai, Vi, and Jarvan's nerfs were decisions made before Cinderhulk was added. They are still decent picks, but they don't have nearly the amount of early game pressure they used to to make up for how much they are outclassed by tank junglers now. The window for these champions to make plays were effectively shortened so that they are only relevant for 10-15 minutes of the game before tank junglers begin to surpass them in effectiveness. Riot sometimes needs to buff champions instead of nerfing the ones that are strong. I understand that sometimes a champion is actually OP and they need nerfs, but it is not the only way to balance the game.
and 
(who I play full AD, more fun)
and 
can do well, but why bother when Sejuani can have 10x more CC and just as much damage. And why even play stuff like 
when you have virtually no mana sustain, and still way less CC.
and you're set.
