Either take away the healing powers from tanks or give healers tanking powers.

[Aravell]

I did hear m3s had some pretty important healing requirements, I dunno if theirs a comp that has cleared without healers on that fight yet, maybe the future design direction should have more intense actual healing for healers, so abilities like divine veil, earth's reply become more "support" to the healer rather then replacing them.

The only reason M3S is unlikely to be cleared with no healers until much later is because that fight has one mechanic that's precisely designed to require a healer.

Fusefield is 8 separate hits of rather high damage over a period of about 20 or so seconds, also the party is spread out at the time, so Curing Waltz wouldn't be useful. The fact that the damage is spread out also means it's harder to cover all of it with mitigation.

Now imagine if more fights were designed with frequent, moderate damage in mind, then tanks would more supplement healers rather than replace them outright.