You'll be fine, just a shift in meta. Tons of new DR mechanics coming for all classes if you read the notes. Heal Monk will still work, but probably as a hybrid-support of sorts. Just the LPS you provide will be like 1/4 of what it is now. Also, much higher stats for everyone via new cube recipe, so consider that as well.
It's unfortunate but i have to tell you that it's way lower than just sitting at 25%. My full geared ancient heal monk from season (1m lps) is now sitting at 170k.
Most of you are missing that not only the spells were nerfed but also they fixed Enduring Ally which, as they stated, affected the values the other spells granted.
- Fixed an issue that caused the Life per Second contribution from Inner Sanctuary - Safe Haven, and Mystic Ally - Enduring Ally to be increased by the Life per Second from other skills
So from what I see the conclusion would be that with that amount of heal the monk is dead (not to forget 170k is what i get. Didn't have some1 to test how much a party member gets. But will be neglectable)