Small post, as we have limited selection, and there’s not really much to say.
Repeater Bolt Throwers: They do exactly what they did before- give Dark Elves some long range shooting threat. With the changes to how wounds are done to warmachines, however, they have become very vulnerable to any other form of shooting. Before, you could depend on the randomization of hits to provide the crew some protection. Now you'll have to hope your opponent doesn't roll a 6 to wound, because if he does, you lose a crew. These guys are very likely to bite it once your opponent has range to it. Still... you may want to take one or two, just so you have that ranged threat. Depends on your army, I suppose.
War Hydra: Last edition, this choice was so common that you would almost always see a player taking two. They were fast, breath weapons were awesome, and they could break units all by themselves.
Now... not so much. A single one might be helpful, but really they're only going to be useful for adding extra wounds to a combat. Basically, it'll function as another chariot. On the first turn it gets into combat (and assuming you haven't used the breath weapon) you'll be causing over 10 wounds to most troops. Combined with a ranked up unit to help combat steadfast, you'll have a good chance to break an opponent. Of course, after that the Hydra isn't quite so effective, but will still help stack up some wounds in combat.
In short, either one is somewhat useful, but neither are great. Given I'm running Black Guard mainly, I could see running either of these choices as support, but probably only one. Will have to work out the points to figure out exactly what.