Well, yes. A pure dot witch doctor build might be to much for this build. It's a matter of how the dmg is calculated and what "incoming attack" means for the energy armor rune effect. If one cast of locust swarm is considered to be "one incoming attack" the dmg of the locust swarm will be reduced to 80 dmg over 3 seconds. Oh no! If however every tick counts as an attack or the dmg is continuous, then you might have trouble with more than one Dot-dmg at once.
If poison dmg will prevent character healing/regen this build is pretty screwed but we have yet to see such an effect.
I don't know how either monks or barbs will be able to perform more than 5 attacks per second but I guess it's possible.
I don't see the problem with gluing yourself to a target. With frost nova and free teleport for 1.5 seconds every time you get hit you should be in a good place. Not optimal but pretty good. And we don't know if you will be able to do enough dmg or not. But if you are very hard to kill, even mediocre dmg will be a pain in the ***. Simple spells like poison dart are proven to be very effective in the arena, so why shouldn't spectral blades do the trick?