Those maps!
I have always objected to the assumption that Austria would absorb Venetia in any but the most insanely overwhelming, and late won, of CP victories. This now cliche annexation always seems like an afterthought by the poster, as if the map ought to have Venetia. The idea of an independent Venetia however, I think is even more objectionable. The CP may have been arrogant (as were the Western Entente) but they weren't so foolish as to create the kind of trouble that an independent Venetia would make; it's an unnecessary flashpoint in a defeated enemy. You see, the Germans and Austrians would be well aware that Italians are already heavily demoralized, worn out and totally unable to continue the fight at this point even if they desired to. Given the casualties for what was obtained even OTL, the Italians had good reason to question certain things about their country's participation. With a defeat, there will not only be no victory to help ease the pain of loss but it will also come with stiff, humiliating reparations, other penalties that impair its offensive military capability in the immediate future and the loss of any hope of expansion in the Adriatic. Italy will also not necessarily be under full occupation at the armistice, since the Germans would not likely be able to ever commit the necessary resources to achieve that on the Italian front unless France - the primary goal - was already beaten. Once that was achieved, Italy would of course, have to agree to peace terms.
Though Italy would accept certain terms, giving up major territorial concessions would be too great a penalty to yield. Besides, since Italy will be neutralized and broken in the way France was, it will be pointless to seize more territory from her or try to carve her up against her will and give that country its own Alsace Lorraine to fester and undermine German plans. Think about it: the border with Italy is already quite defensible and, unlike Alsace, the proposed annexations and puppet states don't provide all that much for Germany or Austria's security that wasn't already there. Nor is Italy liable to be nearly as threatening a country as France was in any likely scenario; it had to be bribed to join the war in the first place and had at least officially been part of the triple alliance before that. It is not inconceivable that it would be amenable to future cooperation in a new, German dominated Mitteleuropa power bloc. Germany and Austria-Hungary could continue fighting take Italy down completely but why keep fighting after so much if it all it gets you is some land for bragging rights? All the more so since the Ottomans were growing tired of war and the Russia could not be ignored for long.
Remember also that the Germans imposed harsh terms on Romania but they didn't partition it even though they completely conquered the nation (which is not going to be the case for Italy at the time of armistice). That country was not split into an independent Moldavia and Wallachia and was actually allowed to unite with Bessarabia. Not only that, but it had few territorial concessions, save the Northern Dubrudja (and control of a few small Carpathian passes to Hungary). In the case of the Dubrudja, the Germans didn't want to do that and only after being badgered quite thoroughly did they relent and allow Bulgaria to take the Northern Dobrudja (and most of that was at least a heavily Bulgarian area, whereas Venetia was not inhabited by the Germans, Magyars or Slavs who made up most of the dual monarchy's population). Ideally, Italy will be brought into the Central powers fold one day, provided the ill will of the war weary people is directed at their government for throwing them into futile war instead of against the German power axis, which is what would happen if Venezia was taken. After all, the Germans will still perceive the main future threats as Britain (which they want to challenge in the Med as best they can) and of course, who needs a future southern front if and when Russia regains its strength for a colossal (and possibly 'final', in military terms) future showdown in the East?