OK - it looks like, with the help of
@lukedalton and
@Mynock especially, we have the outlines of a deal:
Key points include:
1. Austro-Hungarian - Entente mutual armistice and release of all PoWs, likely Entente PoWs first
2. Austrian territorial concessions to Italy, defined by these parameters, implementation beginning the moment of armistice, and completion within five days:
Realistically A-H concession to Italy will be something more than what promised for italian neutrality (the Trentino border will be more favorable to Italy, probably the strategic zone of Tarvisio will be added to the land offered and some concession both economic and cultural regarding Trieste and Fiume)
3. Austro-Hungarian withdrawal from any non-Austro-Hungarian fronts (on Turkish, Bulgarian, German land)
4. Austro-Hungarian release of Romania and Serbia and Montenegro (its "zones" of these countries) from Austro-Hungarian occupation and release of the PoWs it holds from these countries back to freedom in their homelands.
5. A reciprocal pledge from the Romanian and Serbian and Montenegrin governments, or if not these governments, the PoWs themselves, to not resume fighting after release, sort of like old-fashioned prisoner parole.
6. Austro-Hungarian withdrawal from Russian territory and release of Russian PoWs
7. Austro-Hungarian expulsion of the military personnel of other Central Powers' (German, Bulgarian, Ottoman) from its territories and occupied territories within a 48 or 72 hour deadline after the effective hour of the armistice.
8. An Austro-Hungarian embargo against the Central Powers within five days of the armistice, or "with all haste" after completion of the military repatriation and territorial provisions of the armistice, whichever comes later.
When is the likely time, in 1917 for this deal to be first agreed upon between the relevant heads of state, then more importantly, the sealed orders to be issued to commanders, and then the armistice and terms to be implemented and go into effect? Sometime midsummer?
During the long Flanders battles, well after the Neville debacle, perhaps right before, or during, the Kerensky offensive, but before the German Riga offensive or Caporetto? Perhaps about time coincident with the July(?) German and Austrian limited mutinies against naval inactivity?
Austro-Hungarian desertion of the war effort would be a great relief for the Entente and Americans, and a great stress on the Germans and its other junior partners. I imagine the Austro-Hungarians would use the embargo, repatriation of their own troops, and partial demobilization, to guard their own borders (reduced now in relation to Italy) against possible German retaliation, to maintain internal order and preempt escalation of intercommunal/interethnic and labor violence, and seek to ensure the fall harvest and reduction of wartime obligations to its own forces and embargo of of other CPs can stabilize the food situation and help public order over the fall and winter.
Austro-Hungarian desertion of the war effort should be a life saver for the Russian Provisional government. German eastward-looking offensive planning is greatly complicated by the loss of Austrian troops as partners in any maneuver operations or static garrison forces protecting German flanks. German forces still tactically outclass the Russians, and the latter do not have good prospects making any offensive headway against German forces, but even the German assault to seize Riga in September 1917 is put in doubt.
It seems to me that Austro-Hungarian desertion would raise near-panicked alarms about being isolated and defeated in detail in Bulgaria and Ottoman Turkey. Probably first in Bulgaria, which needs to deal with sudden national revivals in Serbia and Romania, even though its containment of the Entente on the Macedonian-Salonika front has been successful thus far.
Bulgaria will probably be seeking a diplomatic exit from the war almost immediately upon seeing what happened with Austria-Hungary. I think for its first offer to the Entente (maybe directly, maybe via the Americans) the Bulgarians would try to hold on to maximum dignity. If they are gutsy, that might mean trying to see if the big Allies would let them out still in possession of Macedonia and Dobruja in exchange for quitting the war or possibly changing sides. That would be pretty gutsy and unlikely to be accepted.
A more realistic offer would be to try to get out of the war with pre-war Bulgarian territory intact, full cooperation with the Allies, demobilization, but no special demilitarization provisions included in the armistice.
Would the Entente go for a deal like this, simply to hasten the momentum of Central Powers quitting the war and German isolation? Or would they more arrogantly insist on more punitive terms or safeguards, like Bulgarian compensatory territorial concessions to Serbia, concession of west Thrace to Greece, and deep demilitarization, figuring Bulgaria both deserves it, and Bulgaria will inevitably have to give way in a few weeks or a month or so, now that Austria is out?
Similarly for the Ottomans. Here I would expect the Entente would hold out for the Ottomans to disarm themselves into helplessness Mudros-style, to enable the Entente to parcel out the full extent of territorial claims. This may slow down Ottoman surrender a bit - they still had not lost Jerusalem yet, for example. But Ottoman capitulation should be a mere matter of weeks after Bulgarian.
Notwithstanding how soon Bulgarian or the Ottoman Empire capitulate, the capitulation of Austria-Hungary, followed by the Austro-Hungarian expulsion of German forces and embargo, will leave Germany very shaken and pessimistic as it goes into the fall and winter. It won't be cause for immediate collapse. It's tactical defensive situation in the west is just too strong for that. [although, anybody want to disagree?]
Calls for peace negotiations and reformed governance will grow louder and spread wider in the Reichstag, on the streets and in media, and in private government discussions.
How will the war end here, and what month will it end? As we get to October and November 1917, the British are delivering terrific punishment to the German forces on the western front in Flanders, although the Germans have a bit of an advantage in the air battle. The Germans are just fortunate that the French are not yet sufficiently recovered from the Nivelle debacle to add a great deal more pressure, and the Americans have not arrived in sufficient mass on the front-line to contribute significantly either. The U-Boat warfare campaign is of declining efficiency and efficacy compared to its mid-summer highs.
The Russians do not really have any offensive impetus, but are an army in being, with only long-occupied and highly damaged and picked over Poland, Lithuania, and Latvia available to exploit for its harvests. And Germany always needs to worry about the consequences if the traitorous Austro-Hungarians go beyond their armistice and self-neutralization from the war and came to an agreement to allow Entente forces, Italian, Russian, Balkan, western, to advance into unguarded southern and eastern Germany through Austria-Hungary's road and rail network. Worse yet, as much as Berlin may fear this scenario, it does not have the troops and formations to cover this basically unguarded frontier.
Under these strained circumstances, I would think the Germans would not have much hope for massing the bulk of their forces to gain numerical superiority in the west for a spring offensive to beat the arrival of American reinforcements - while also being confident in having a secure rear to the east and southeast. The Entente, mainly British Empire, force, kept on doing major assaults in Flanders into November, and anti-Ottoman operations into December and the winter, making Jerusalem, if not also Constantinople and Damascus, a Christmas gift for his majesty. So, the Entente could genuinely consider launching another major western front offensive in the springtime. Or they could wait till summertime to let the Americans and French pay more of the butcher's bill. It all depends whether they value haste in ending the war more versus managing and balancing losses across the coalition more.
Germany could quite plausibly sue for peace, seeing no way for its situation to improve, during the winter 1917-18 months, or early spring 1918, even before test by a major 1918 Entente offensive. How would such an armistice compare with OTL in its territorial, reparations, and disarmament terms.
I would note that while I'm sure there would be more concrete definition of Entente and even American war and peace aims in the final months of the war, there is not guarantee we would see exactly what we saw in the OTL 14 Points. Those points, and some parallel points raised by Lloyd George, were significantly released in response to Lenin's embarrassing release of the Allied secret treaties, which would not happen here, in an ATL without the Bolshevik revolution.
However, France would certainly demand and get back Alsace-Lorraine, and the western powers would probably feel most comfortable with an armistice forcing the German Army back behind the Rhine, regardless of what is done, or not done, to the political status of the Rhineland or the Saar. However, it is not foreordained that Germany would suffer eastern territorial losses to serve the interests of a new Polish state. The idea certainly was in the air already, but here it is complicated by the continued existence of the Austro-Hungarian Empire and a Russian Republic with suzerainty over its own set of Polish lands. While both Austria-Hungary and the Russian Republic will be allowing greater or lesser degrees of Polish (and other ethnicity's) autonomy or even home rule, neither is likely to go out of their way to push a project to "unify" Polish lands. The Tsarist regime early on in the war expressed some greed for Austrian and German Polish lands, but likely by this stage in the war, the leading parties in the barely holding on Russian Republic will be Socialists of varying kinds, wanting to show they are eager for peace, fond of the slogan "no annexations or indemnities" and not wanting to be seen making demands that look like they would slow down the end of the war. So that raises significantly the chance of the status quo international partition borders dividing Poland remaining, even while Germany's borders with Denmark, Belgium, and France change.
