I don't think the zoanthropes do much in 5th.
Never bothered me in 4th, and in 5th there is a plethora of fearless troops (and everyone not fearless can be made immune or don't care to the ability).
Not that there weren't this many before or anything, but with the drastic effect of close combat you'll see people taking fearless instead of -12 modifiers. It's easier to survive.
And zoanthropes do nothing in this environment.
Oops, put my seer hat on for a moment. Sorry.