I just listened to this podcast from
mixinglight.com
According to the guy in the interview, Apple is still selling nMP because they have a ton of components and inventory left that they have to sell otherwise they pay hefty penalties to their suppliers. I don't know how much of that I believe, but if you look at where we are at, with a three + year old machine, at 2014 prices, it does make some sense.
The nMP has been one serious miscalculation from Apple, and it's pushed away a large portion of the Mac Pro user base to other platforms. Many can't stick around and wait on products that may or may not ever be developed.