It's dead in the sense that it's pretty much played out, and today, it would be difficult to exceed the works of webern, dallapiccola, boulez, etc. etc. since they did it so well. Also, there are some weaknesses to the technique (including a kind of homogeneity of sound) that need to be worked around.
It's as dead as, say, romanticism, or renaissance counterpoint, or classical form, and for the same reasons.