Even if we go by the logic of saying, since everyone now has increased HP, the damage from survival hunters seems more manageable, it still doesn't change the fact that their damage is legit INSANE compared to other classes. Sure, they don't have the spread pressure, and easy targeting of a boomkin, but they have crazy single-target pressure instead.
Now you argued solely for how games would fare in terms of the survival hunter being in mid. Even if healers do have more time to react now, I do feel like under coordinated circumstances, they will have the same effect. I.e. during hard swaps. I also think that survival hunter getting to pump damage into someone in mid is going to be huge in terms of landing kills overall. These are solely the damaging aspects.
Now we look at the toolkit overall, still with the assumption of survival hunter playing in mid. Aside from their insane damage, they also have harpoon, which is a 5-40 yard range. trucking. 40. ARE. YOU. JOKING. This means that no ranged class can actually max range them, since the casted spells with the longest range is also 40 yards. On top of that, the overall mechanic of that spell is so wonky that you harpoon pretty much up, down and through almost everything. Imagine if charge had the same pathing. Hot damn.
The overall wonkyness of the harpoon spell is less relevant in mid where the field is more of a flat landscape with no LoS. However, the sole range and the added root for a short duration of CC is super huge on its own.
Survival hunters, like any other hunter, also has a pet which has the possibility of having roar of sacrifice, given that the pet is specced into cunning. Also, 40 yard range. This is important to note to understand the overall utility. Because, not only will you not out-range your pet by harpooning on to someone (given that your pet is near you as you harpoon), you also have a wide range of opportunity to RoS a team member. Now, with a wide range of pet choices, some more utility is also added depending on what pet you choose. For instance, you have the possibility to get a pet which can cause mortal wounds. Reducing healing effects by 25%. That. Is. Huge. Survival hunter also has wing clip, which reduces the targets movement speed by 50% for 15 seconds. Slows at 19 means A LOT. Some classes sacrifices a lot of resources into having someone slowed, and some for a duration that is not even close to that of 15 seconds. Next up is survivalist. You AND your pet receives 15% health over 10 seconds after landing a kill. With the current health pools, that is a lot of healing, granted you get a kill. Some classes barely out damage that heal alone (kek rogues, rip). Another utility that is important to mention is track humanoid. Hunters can easily track people's movements around the map, looking at who's about break off etc. etc. without targeting them. This gives them the upper hand in being able to read most situations simply because of the easy-to-get information on what's currently going on around the map. And last, but not least, freezing trap. A class that already excels at so many things gets an 8 second cc ladies and gents. "But mr. they have to land it, it's a skill shot". Harpoon into trap, or literally just walk on top of someone and throw the trap at your feet. This will guarantee that your trap lands.... And if you're THAT bad, add in a wingclip before throwing the trap, and if you can't land that, well, then you should maybe look into playing mine craft or something, I don't even know. Point being, you. have. a. lot. of. shit. compared. to. a. lot. of. classes. Hell, you can even place it at highly used routes, i.e. the opening of tunnel and just let the trap chill there if that's your thing. It'll get the EFC out of stealth once triggered, and a lingering class or whoever happens to be near can take it from there yada yada.
Now to the real part where Survival hunters excel. You turn off your tunnel vision for 10 seconds to cut off a healer/mage/other hunter (let's just pretend that hunter isn't a survival hunter)/any other important class who is getting into position in order to meet/escort/peel for EFC. You are now in isolated situations of 1v1, 2v2, and at max, 3v3. This is where survival hunters become INSANELY strong. Simply because there is near no one with the same toolkit in terms of damage AND utility, except for boomkin, which in terms, both classes have different trade-offs. Your ability to dish out more damage than literally everyone else alongside with aforementioned toolkit, should give you the upper hand in that 1v1, 2v2 or 3v3 situation 10/10 times (taking into consideration you aren't running around with 100 health as the situation occurs). Aside from all these situations, survival hunters also excel at cutting EFC's. Remember when I mentioned the wonkyness of the harpoon spell? Yeah, this is where it gets really fucked. I have literally been harpooned from Africa, where the hunter flew under the fence at ally ramp, but also on top of horde GY / horde ramp. The spell is absolutely broken and doesn't seem to follow the same ruling as other gap closers for some reason (i.e. warrior charge).
So.... You are basically looking at a class with INSANE damage, A LOT of utility and a broken gap closer. There is no other class that really compares at the moment. Literally. Closest is being a boomkin, which will exceed at other things, but at the end of the day won't outperform the survival hunter in the role that the hunter is supposed to play.
Coming back to the argument of survival hunters now being healable due to the increase of overall health in the bracket. The increase in health also in terms mean that in situations where survival hunters just gets to dish out damage, whether it being 1v1 or in mid is irrelevant, because they get to ramp up almost exponentially compared to other classes. This is due survival hunters broken damage compared to other classes. The classes that could somewhat manage survival hunters used the advantage of low health pools. Now when that is gone, survival hunters will just keep pulling ahead given the extra time frame that comes with the increased health.
So...
If feral druids were banned in WoD, I don't see why survival hunters shouldn't be in Legion.
Summarizing:
-incomparable single target damage.
-Roar of Sacrifice (40 yard range).
-Mortal Wounds.
-Harpoon (40 yard gap closer with root, and an overall wonky mechanic in terms of ignoring terrain).
-Survivalist (15% health over 10 seconds to both you and your pet).
-Track humanoid.
-Wing clip (50% slow for 15 seconds).
-Freezing trap (8 second CC).
-Outmatched in isolated situations.
-can take upon most dps-related roles and do them a million times better than any other class (i.e. mid / linger / offence / defence).
Now, I didn't even go to mention how ridiculously easy it is to play this class to the point of simply just being effective. Of course "mastering" (I laughed and puked a little at the same time there) the class is going to be different. You will see differences between an average, and a really good hunter. But the range from "average" to "good" is basically non-existent.
If you allow this class, which can literally be played by someone on life support playing on a tablet, then something is straight up wrong. Especially given that feral was banned in WoD. Also, if you're reading this and you play a survival hunter, I hope someone unhooks your life support.
I wrote a bible, I know.
TL;DR. No, don't allow survival hunters, ban them. Read the bible above to see my points on why I think so.