Good news! I have spoken with those in-the-know on the AT&T Natural Voices project and ... here's what I can divulge:

The future is in flux (well, of course)!
The server component is not going be offered to the public going forward.
The future of the desktop portion of Natural Voices looks more promising.
WRT the desktop, we're talking weeks, not months (yes, I'm allowed to mention that )

As the saying goes, everything in the world is tentative. When I learn more, I'll post it here!