Healer never had just one problem. Tanks and DPS getting buffed upwards while leaving healer in the dust doesn't make healer better or shift the problem to something else. In fact it just means healer gameplay gets powercrept further the moment tank and dps starts getting more healing actions to the point no-healer clears are done on same patch - as shown in Dawntrail.
Healer falling behind tanks in DPS is one problem.
The engagement of gameplay being monotone is another problem.
Healers did not have much of an issue with healer DPS because engagement was important, but the moment tanks start being able to replace healers in such a significant degree, it only highlights a new problem of healers -- the point that the role imbalance is causing issues with even keeping a healer on a party because they offer far too little in a general overview of the gameplay. Just making 'more to heal' will never be a proper solution because of ilvl. ILVL will eventually reduce the burden or even need of healers from 2 to 1. Except we're already at the point on patch release before BiS where we can go from 2 to 0 healers on the current hardest available content difficulty.
At this point I don't see any solution with people not wanting healers to be good at anything other than healing but never making the healing part ever required in anything other than maybe at best 3-4 pieces of content before it gets invalidated again. Even asking for parity is too much of an ask now.