So, assume that Napoleon ultimately decides to destroy Prussia for good after his victory at the Battle of Friedland in 1807. The Duchy of Warsaw would still be created.
How would he divide the spoils? Here's what i think:
My guess is that a rump Hohenzollern state would linger on in most of Brandenburg, with a corridor to connect Berlin to Stettin.
Pomerania, Upper Silesia, the Vistula estuary, parts to the north of Middle Silesia, and Warmia (which was once part of Poland) and some chunks of southern Ducal Prussia would be given to the Duchy of Warsaw.
The northern remainder of Ducal Prussia would go to Russia, just as a thrown bone to Tsar Alexander.
Perhaps Lower and most of Middle Silesia would go to Austria, to keep them sweet. If not, these could be given to Saxony.
Is this at all feasible? What are the effects of a destroyed Prussia on the remainder of the Napoleonic Wars?