What new class and or battle mechanics do you wish 4.0 will bring?

[Shurrikhan]

Agreed. This does call for adjustments across most classes, but I feel it's needed at this point. It's only going to get worse as more tanks and healers are added to the rosters, so the time to fix it is now.
Agree here as well. This is basically how I feel about tanking. I get that healing, much like tanking, call for a very specific mindset and have responsibilities that not everyone can get into, but the DPS obsession Heavensward has exacerbated is not helping overall. Sure, you're seeing more tanks and healers, but you're effectively blurring the lines to the point some see a tank as a DPS with defensive cooldowns and a healer as a DPS with cure spells.

But that IS what they are. In every MMO! The only question is whether a given option (i.e. dpsing on a healer) is worth the resource cost (time, mana, and whatever cooldowns can be exchanged for additional time). And I'm damn glad that I actually have that decision to make, instead of just being a raid frames heal bot. I like that I actually can decide between pushing dps and taking less damage (though sometimes that particular decision can feel a bit forced or conventionally driven). Above all, I like that these options on each incentivize awareness of each others' capabilities, styles, and cooldowns to play optimally.

The solution to this, as far as I can tell, requires two things. First would be designing one or two "easy" healers, and make the rest intermediary/hard healers (either more mechanics to look out for or buffs to upkeep or a separate resource). Make the results similar enough that both echelons are competitive despite requiring varying skill levels. The second could be to increase damage dealt by dungeon and raid mobs, which would force healers to focus on healing. Perhaps make MP conversation more important so that a healer is sort of forced to conserve MP for heals rather than "waste" it on DPS abilities.

Three issues here:
(1) By decreasing the effective MP generation of healers, you reduce time spent actually doing things. This may appeal to some, who like idle periods, but is slap to all those who do not and like the current level of healer activity.
(2) By decreasing the effective MP generation of healers generally or specifically on offensive casts, you adjust the the current cost-reward balance of dpsing. Pushing this too far at all makes the decision non-viable. Moreover, any change to healer dps option viability constitutes a change in tank behavior (more dps-orientation) or (where such a tank shift is impossible) larger pulls, etc. Be careful what you ask for.
(3) Increasing mob damage in general, when many boss or key mob skills already or very nearly one-shot non-tanks, reduces the total number of options available for handling mechanics and invites role arbitration. Imagine for instance a player who does virtually nothing for 99% of a given fight, but is necessary because at a certain point the group will otherwise automatically wipe if he is not present. That is the end of the slippery "real tanks" slope you're suggesting, where dps for tanks, healers, and pure dps fall out of balance, their capabilities made irrespective to each other or any common goal. I'll admit that certain tune-ups could be helpful, primarily in my opinion by increasing dps-to-healing synergies, shared resources, and alternate uses for idle time for healers. (And perhaps a number of utility improvements for DPS as well that provide alternatives to required full-time tank or healer needs — remember when CC was a thing? That said, I honestly do not think tank dps has been absurdly high atop their overall raid contribution by any means since the HP buff / AP nerf.) What inventive compositions could have pulled off in multiple ways now requires a slot, which can be completely out of touch with the actual objectives of a fight in pursuit of its "role", dedicated specifically to a tank just because one in three mob attacks will unavoidably one-shot non-tanks, as if due to a "composition debuff". If you want to increase healer pressure without cutting out possibilities, the buff to mob damage needs to somehow take effect over time, wherein skillful handling of the mobs still allows for other options, while healing needs are still noticeably increased as to reduce idle or dps-capable time and/or reduce mana budget.

I can get behind tank stuff getting toned down for the 70 level cap, if and only if the design is changed so that tank stances matter. This means that if you're a WAR in Deliverance trying to tank a boss, that boss is going to crit your face off. If you're a PLD in sword oath, the boss will rip you to shreds. If you're a DRK that's not in Grit, you'll quickly become a bloody stain on the ground. This way you have a better scope of expected raid DPS for fights while also not needing to nerf tank DPS for soloing and questing.

Again, I do not see why you are so keen on removing options from the game. I get the feeling sometimes that even if you were to be playing a fight on minimum ilvl or in some manner of challenge mode, you would flip if a tank survived a tankbuster without tank stance, nevermind what CDs or shielding he had present at the time. Gear is always going to eventually allow for reduced mitigation requirements. Why then should tanks be barred from scaling with it as to best run the edge of survival and output? Could some retuning be of use? Perhaps. But minor, and likely based further in the actual toolkits and whatever 'role' crossovers exist therein, rather than by purposely condemning a stance to OT or MT only.

Alternatively, how would these changes to non-tank stances not carry over into solo content? Would you be arbitrarily retailoring them for boss fights? Would you be introducing a crushing blows -style mechanic? And lastly, why should tanks have two different sets of stance balances for solo and group content? If anything, shouldn't you be simply buffing the tank stance side as to be less dependent on incoming damage for its viability, better able to benefit directly from attack power, etc. (see stance-dependent self-heals, and Paladin's lack of them)?

Indeed. All it'll do is perpetuate the broken meta and try to force jobs into one of two columns.

This I'll agree with. But were new healers or tanks added interested only in filling their "role" irrespective of actual overall outputs, it scares me to think how broken that new meta would be.

Tanks and healers exist as a means to accelerate clear times through means that dps alone cannot provide. That does not mean that they need to be able to deal a certain amount of dps, or whatever certain percent of what a pure DPS does; that much is a mere "fun" or "quality of life" addition to allow a dual scaling of the role in question, to better fit the situation and reduce waste compared to the theoretical potential of the job while allowing for a more consistently high level of intensity even across varying incoming levels. But it does mean that their use should always be made within the mindset of what best accelerates clear time, which... naturally enough, comes down to dps. It can be derivative, so many mother's sister's cousin's roommate's teacher's fiancee levels of indirect, but one's reason for taking a healer or dps should always be clear time, and weighable against alternative compositions within the given fight. They should not be there merely to prevent death by composition error, let alone acting like an enmity-smoking meat shield or frenzied to idle-pilot raid restorer (whose only rate of intensity is no more and no less than incoming damage, never what all he can accomplish between those periods). Some of these means by which they improve clear rates may be required, but ideally, in my opinion, they should not be a mere checklist of needs; the added mitigation, restoration, and utilities of tanks and healers should always equate to a certain equilibrium with dps, and viable in more analog and experimentable fashion. But that requires balance, not merely latching onto (derivative) "roles" for "roles" sake.