The WD will be fine. The summoner WD will be non existent. Personally though, aesthetics irriates me to no end, that hunch backed, diseased, hand twitching is NOT what I want to see in a supposed hero of sanctuary.
The summon necro, since you mentioned him, is viable even in hell act 5. I would know. I have one.
And no he does not sit around twiddling his thumbs while skelly army does all my work. That far in the game, the skelly army requires curses and damage from you. Not easy, but it works.
I think that's why. The WD was expected to fill the necromancer's shoes as a class that could play as a summoner, and he can't. Actual play testing in the stress aside (which I've done)...the numbers alone tell you pets will not work, even in normal don't get me started on higher.
Poison Dart does a combined 140% weapon damage in a single hit. NO runes.
3 zombie dogs + gargantuan + 4 spiders ALL hitting ONE target = 116% weapon damage.
So what's the damage reduction on the darts? If I remember correctly, the UI does not even let you assign dogs to Mouse #1.