There has long been Antagonist available for enemy cast bar display as well as BigWigs for boss ability bar display. As well as Chronometer, ClassTimer and other mods for your own spells/DOTs. Some/most/all of those are very likely to be updated for the 2.4 combat log changes.
So for those who want NECB back exactly as it was before after 2.4, I wish you the best, because its not a big deal here ;). Well, it might be if none of the Wowace ones are updated, but until then it isn't :D.
This is not entirely true. While there are addons that can replace most parts of NECB, there is none other (to the best of my knowledge) that tracks diminishing returns. There is ProxDim that does it in arena on top of Proximo, and that could use some love too. :P