For the sake of argument lets say Napoleon wins in Russia (manages to draw the Russians into a battle and crushes them), forces Alexander back into the continental system and eventually makes a permanent peace with the United Kingdom. France dominates the continent. In such a scenario who would be the most likely bride for the King of Rome, Napoleon's heir? A Bonaparte first cousin? Another Habsburg Archduchess? One of the German Princesses (Bavaria or Saxony being the most likely)? A Russian Grand Duchess? Or even one of Napoleon's former enemies, like an Iberian Infanta or a Princess of Sardinia/Sicily? Or even someone I haven't thought of?