Tank Balance

[Reynhart]

The current setup works pretty well, I think: serious tanks can go all in for DPS maximization

For me, the second part of your sentence completely contradicts the first.
And I fear this will bite us really hard if they decide to add other tanks in the next expansions.

Adding a real "gameplay" for mitigation would lift a lot of complains because player skill would "blur" the gap between each tank, like it does with DPS.