Self-sustain is not a mandatory feature of tanking. You have an entire role dedicated to keeping you alive in co-operative content. The main benefit of adding in self-sustain is create exciting gameplay opportunities for tanks to make clutch saves. But it shouldn't replace the need for healers. A lot of the community backlash against the design choices on WAR this expansion aren't just coming from other tanks demanding parity. It's coming from healers as well. Upward balance through buffs is not an option, and I don't think players will support another expansion of this.
Part of the problem is that for self-sustain to be interesting, it needs to carry an element of risk. Most of the self-sustain approaches that we've seen eliminate risk, because they are either passive effects or they're available on demand to quickly bring you back to max HP. If you want to reintroduce risk, then you need to give players a reason to play chicken with a two digit HP total. That may mean having a heal that's only really effective when you're at lower HP totals. Or perhaps it may mean having a heal that's more effective after a tankbuster or higher damage hit.
The other issue is that it shouldn't be readily available. The problem with tying healing to defensive cooldowns is that you can afford to hold them in reserve until you need them. Equilibrium is literally just there to add extra HP on demand. Tying healing to offensive, resource-gated actions is a better approach, because you have less control over when they come up. In the event that the job in question has a spam burst window (IR/Del/Req), you just need to make it such that the 'free' hits have no self-healing attached.
We're coming into a new expansion, and that tends to be a time for stealth nerfs. My recommendation would be to be proactive and find compromises that are more balanced for WAR and reward skilled gameplay. I personally don't mind if there are some discrepancies in self-sustain, but if they exist they should be offset with unique strengths in other areas. That may mean that jobs with weaker self-sustain have unique access to better movement actions including raidwide movement speed buffs. But you can't have it all, so choose wisely.