I think too that the name Moto Guzzi belongs to Mandello del Lario and vice versa. But I think that in the (very) old factory it's just not possible anymore to produce modern motorcycles according to modern quality standards.
The ideal situation would be a new factory in or not far from Mandello and the offices and Museum at the old site.
But the fact that Piaggio didn't show much interest in Guzzi at all (if one bids enough, it's theirs), makes me believe that they will sell the old location for big bucks to some real estate company. Worst case scenario: Piaggio gives Guzzi two years to raise sales, and then decides to terminate the whole bunch and sell the brandname.
This is all speculation from my part and I can't be held responsible if /when any of this turns out to be true...