We need to do something about Tanks and Outgoing Damage from Bosses

[ForsakenRoe]

The reason 'Tank Self-Sustain' is a problem, currently, is simple IMO: HP restored is 'permanent'. Once you heal the HP back, it doesn't expire, it's there until damage removes it again.
So wouldn't the issue be semi-solved, if all these Tank healing actions were converted into short-duration Barrier effects?
With Barriers, the Tank gets all of the self-sustain that the current Healing provides, but it requires them to be more proactive in timing the Barrier application, and if some of the Barrier isn't consumed, it's lost.

For example:

Holy Sheltron - 4 stacks of 250p barrier, lasts 12s. Using another Holy Sheltron adds 4 more stacks, and refreshes the duration to 12s
Holy Spirit/Circle, Confiteor, Blade combo actions - Adds a stack of 400p barrier, lasts 9s. Adding a new stack also refreshes the duration to 9s
Divine Veil - Applies a 400p barrier to party, in addition to the '10% of PLD's HP' barrier effect. Both are added together to make one buff (buff cap problems), and lasts 30s
Guardian - The duration vs CD balance means that this isn't an issue I think
Clemency - Horrendous DPS loss as it is, so is probably ok to stay as it is

Bloodwhetting - Applies a stack of 400p of barrier (as it does now). Adds one stack of 400p barrier per enemy struck via weaponskill, lasting 12s. Adding more stacks does NOT refresh the duration
Equilibrium - Applies a barrier of 1200p, plus 5 stacks of 200p barrier, lasting 15s
Shake It Off - Applies a 300p barrier to party, in addition to the '15% of target HP' barrier effect. Both are added together to make one buff (buff cap problems), and lasts 30s. Also grants 5 stacks of 100p barrier, which also last 30s
Thrill of Battle - The healing this provides is not an issue, and removing it will cause more issues than it'd solve
Damnation - Applies 5 stacks of 200p barrier, lasting 15s

Abyssal Drain - Applies a barrier (imagine it's made of the enemy's blood) of 500p per enemy hit, lasting 15s
Carve and Spit - Applies a barrier of 500p, lasting 15s
Shadowed Vigil - Applies a barrier of 1200p, lasting 15s. If this barrier expires before being fully consumed, applies a heal equal to 50% of the remaining barrier strength.
The rest of DRK's kit is already very barrier heavy, and we see that DRK is the 'least problematic' of the Tanks when it comes to 'Tank is too self-sufficient and refuses to die even when the party is all dead'

Aurora - Applies 6 stacks of 300p of barrier, lasting 18s. Using a second charge adds another 6 stacks, and extends the duration back to 18s
Heart of Corundum - Applies a barrier of 900p, for 9s. If this barrier expires before being fully consumed, applies a heal equal to 50% of the remaining barrier strength.
Great Nebula - Same logic as Thrill, changing the 'heal' this provides would make more issues than it'd solve, and the 2min CD means it's not too problematic

There we go, not only is the problem curbed (Tanks are no longer healing for ridiculous amounts), not only are the Tanks just as strong as before (ie they didn't get nerfed, as their selfsustain is pretty similar, just they have to be more proactive with it due to it being barrier-based), not only are the Tanks more thematic with these adjustments (the Tank role is defined by 'mitigate damage that is taken', and Barriers are more thematic to that than 'take the hit and then heal it back' I'd argue)...

Not only all of that, but with these, the Tanks are actually getting super-buffed. Imagine being a WAR, as we know them now, for something like FRU's TBs. I hear a certain bearded streamer was on about how Holmgang is so critical to WAR's defensive kit, because Bloodwhetting is weaker than its counterparts, Damnation doesn't have an additional mitigative aspect (in the way that Guardian has the barrier, GN has the 20% HP boost, etc). Well, with these changes Equilibrium would be an on-demand, 1200p+200p barrier, once per minute! Bloodwhetting would allow you to prep at least one stack, in addition to the Stem The Tide effect, giving 400p+400p of barrier from that, too.

But, on the flip side, for the most part once a Tank with these changes in place loses some HP, that HP is gone for good, until a Healer does the Healer's job, of Healing the HP back. Eventually, without a Healer left alive (as is the case with the OP's example), the Tanks will have their barriers fall off, and their HP will eventually whittle down to zero. They can sustain themselves for longer via skillful gameplay, rotating their barrier effects, etc. But not infinitely.

I believe this shows, you do not need to 'nerf' the Tank's self-sustain potential, to solve the problem. This is a buff, a fairly sizeable one at that, when you think about it, but it'd still solve the issue from the OP.
So if anyone claims it's a nerf, I'll point to the slides from Liveletters that say 'Job effectiveness may vary due to player skill'. Being unable to rotate CDs effectively to make full use of the barriers is a textbook example of 'skill issue'.

Also, last thing: with these changes, comes potential new avenues for optimization. Where a PLD would spend their Divine Might proc might be adjusted around these changes, because spending it and generating a new stack of Barrier would refresh their 9s timer, potentially allowing them to further extend their mitigation coverage (ie carrying the multiple stacks gained from the Confiteor combo further along in the fight, to cover more damage overall)

[ForsakenRoe]

Start an enrage timer once all raising jobs are dead.

That is the general gist of what I'm saying here:

For example:

Holy Sheltron - 4 stacks of 250p barrier, lasts 12s. Using another Holy Sheltron adds 4 more stacks, and refreshes the duration to 12s
Holy Spirit/Circle, Confiteor, Blade combo actions - Adds a stack of 400p barrier, lasts 9s. Adding a new stack also refreshes the duration to 9s
Divine Veil - Applies a 400p barrier to party, in addition to the '10% of PLD's HP' barrier effect. Both are added together to make one buff (buff cap problems), and lasts 30s
Guardian - The duration vs CD balance means that this isn't an issue I think
Clemency - Horrendous DPS loss as it is, so is probably ok to stay as it is

Bloodwhetting - Applies a stack of 400p of barrier (as it does now). Adds one stack of 400p barrier per enemy struck via weaponskill, lasting 12s. Adding more stacks does NOT refresh the duration
Equilibrium - Applies a barrier of 1200p, plus 5 stacks of 200p barrier, lasting 15s
Shake It Off - Applies a 300p barrier to party, in addition to the '15% of target HP' barrier effect. Both are added together to make one buff (buff cap problems), and lasts 30s. Also grants 5 stacks of 100p barrier, which also last 30s
Thrill of Battle - The healing this provides is not an issue, and removing it will cause more issues than it'd solve
Damnation - Applies 5 stacks of 200p barrier, lasting 15s

Abyssal Drain - Applies a barrier (imagine it's made of the enemy's blood) of 500p per enemy hit, lasting 15s
Carve and Spit - Applies a barrier of 500p, lasting 15s
Shadowed Vigil - Applies a barrier of 1200p, lasting 15s. If this barrier expires before being fully consumed, applies a heal equal to 50% of the remaining barrier strength.
The rest of DRK's kit is already very barrier heavy, and we see that DRK is the 'least problematic' of the Tanks when it comes to 'Tank is too self-sufficient and refuses to die even when the party is all dead'

Aurora - Applies 6 stacks of 300p of barrier, lasting 18s. Using a second charge adds another 6 stacks, and extends the duration back to 18s
Heart of Corundum - Applies a barrier of 900p, for 9s. If this barrier expires before being fully consumed, applies a heal equal to 50% of the remaining barrier strength.
Great Nebula - Same logic as Thrill, changing the 'heal' this provides would make more issues than it'd solve, and the 2min CD means it's not too problematic

With the 'enrage' being 'the tank eventually dies to the incoming chip damage dealt to their HP, because of the holes in their barrier uptime'. Just, instead of it being a static 'everyone who can res is dead, you have 2mins before auto-wipe' (which would feel hamfisted/'artificial' as a solution, for lack of a better way of describing it), it'd be 'the tanks can try to extend the fight as long as they can, and it's dependent on their skill as a player as to how much more time they can buy to try to eke out a victory', giving the control of the 'time at which the fight 'enrages'' to the player, not the devs. Player agency and all that

Either that, or make Phoenix Downs useable in combat (but they have melee range so they're still finicky to use, and they cannot be Swiftcasted so a hard res is still more preferable) so we don't have to watch Johnny WAR try to solo a new Raid a few hours after release. On an alt, I got the same thing: everyone except one guy (A WAR, who'd have thought) died to various things (myself, I died to the damage of the phase transition effect, not the 'gotcha'). The WAR then proceeded to try to solo their way through all of the second part of the fight, got to the 'third section' as it were, and promptly died to a stack marker because yeh, stack marker. Then they said in chat, and I quote, 'yeh so that's basically all the mechanics'

Brother, if anyone wanted to see the mechanics, we'd have watched a guide on YT before going in