On the other hand, there's a very significant chance that Apple will simply declare the MP6,1 to be the "death of the pickup truck", and drop the line - citing poor sales for a system that nobody asked for.
While I doubt Apple will drop the nMP soon, we all need to face a simple fact: the market for high-end workstation machines is steadily shrinking, and it will turn into a true niche market sooner than most of us want it to. As it stands the availability of cheap commodity components is on the borderline of making really fast machines almost disposable, as evidenced by an earlier post of mine in which a guy I worked with built a machine just for rendering, used it for one job and then promptly sold it.
Which is to say, I don't think Apple ever expected big sales from the nMP, simply because the days of big sales from desktops are over. As it stands I will probably never buy another desktop from Apple, simply because for my work (print and digital pre-press/production) the combination of faster CPUs and Adobe's complete lack of interest in making their apps multi-threaded means a fast i7, an SSD and enough RAM is more than enough to handle almost anything. I will still have a PC desktop for gaming, but, even there, the advances we're seeing in gaming laptops are pretty amazing.
I don't know if Apple will ever abandon their pro workflow, but I think they will transition it to other form factors which, obviously, will piss off some people. Given the enormous advances Apple is making in the performance of their mobile chips, god only knows what we'll be doing on our phones in ten years.
And, for people who can't see a post about an iPhone/iPad without foaming at the mouth about how they're toys, I remember sitting in a newspaper's composition room in 1987, surrounded by people banging away at $80,000 dedicated typesetting terminals, listening to one of them bitch about having to use that little, toy computer in the corner to make an ad. She then went on to explain why that Mac never be of any use to anyone. Seven years later all those people were out of a job and I was running the pre-press department for a commercial and financial printer using those little, toy computers.
Rant/digression over. We now return you to our regularly scheduled bitching/speculating.