At least horde-side there were only like 10+ players on the whole server at any one time. You were lucky to find even enough to do a heroic 5man.
I would expect that this much of a population collapse would translate into the server not being worth keeping live any more :/
and I say that as a cata-specific player.
It's not a bundle of joy that they are turning it off, but I understand.
Related to some of the other posts in this thread. How Nelth got to the state it's in now is kinda water under the bridge, but I'll mention this since I was there and paying attention for the whole population collapse and such. It was in a sense a perfect storm that drew players away from the relatively-buggy Cata server to the much more interesting-at-the-time (and possibly less-buggy) wrath/outland/etc servers. Then once those servers were up, Warmane devs began working on Nelth in earnest, but it was too late. The players had largely launched over to other expac servers. In that short interval the devs got a LOT of work done on Hyjal and some done in Deepholm, as I recall. But then with the players already gone, what was the point of continuing all that, I guess.