Most of the CP-victory scenarios where Italy isnt placed in the CP camp have Italy falling before France and Russia.
So Im wondering what would be the consequences of Italy being knocked out of WWI, with the Central Powers still loseing the war?
When, after Caporetto? It makes a HUGE difference to the way the war ends and may prevent a total implosion of the Austro-Hungarian empire. I will still break up, but they cold prevent Bulgaria from falling and act as a resource farm for the CPs. 1918 is then all about demobilizing soldiers and turning resources back to growing food and repairing infrastructure. Bulgaria could then survive, though the Ottomans are doomed. Tensions will mount until Germany surrenders and then the Empire splits in two. The allies will have a harder time supporting Serbia, which means it won't be as large and the Austrians are busy sticking it to the Czechs.
Hungary might then be much more stable without a communist revolution and be able to beat the Romanians, though once the Allies are able to move through the Bosphorus, the end game is coming. Bulgaria might be able to cut a deal, but they will lose some territory at the peace table.
Without Italy, the Austria state might the be able to get a better deal, as without a means to go after her, the Allies decide its not worth the trouble, cutting a deal to allow the new Austrian state to keep its German minorities close to its borders, i.e. the Sudenten (most of it), Pressburg, disputed areas in Carinitha, and perhaps all of Slovenia. This would leave a nation of about 10 million people with a strong industrial base and a weaker Czechoslovakia, which then might find itself as part of the little Entente if so inclined. The early end to the war for Austria-Hungary leaves Austria much more stable and less starving during 1918, having had an extra year of 'peace', meaning it is able to de-militarize the nation to a sustainable degree, though shortages and banditry from deserters will continue.
Italy will be a mess after their defeat, probably seeing a Socialist revolution and civil war. It will be a miracle to see them pick up
anything in the war, but with the Empire breaking up, it is possible to see the Italian areas leaving of their own accord and the Austrians not caring enough to stop them.
As to the Western Front, it means little except for the Allies regaining the several divisions lent to Italy, heavily outweighing the loss of the single corps of Italians in France. Though I do see some divisions tied down in Italy, trying to prevent a revolution or at least fighting communists. The end for Germany stays the same, though with the fun realization that they would be the first or second CP to surrender, as Bulgaria is not likely to go first with Austrian support, nor is Austria-Hungary pushed over the edge by the Italians and are able to muddle on until the Allies decide to cut them a deal.
That brings up another interesting question: do the Allies cut Austria-Hungary a deal when there is no effective way to attack them? Without Italy, Romania is still out and not likely to rejoin in the same way as historical in 1918 against an undistracted Habsburg state. The Balkans is now a bottle neck where the Austrians can transfer their heavy artillery and aircraft to support the wavering Bulgarians, probably keeping them in the game indefinitely, thanks to the terrain and the Austro-Hungarian experience in mountain warfare. With no active fronts besides the Balkans and plundering the Ukraine, Austria-Hungary will be much more stable politically and socially than OTL 1918. The breakup is going to happen, it is just a matter of when. The nation won't dissolve into civil strife like in OTL 1918, thanks to being able to spend a year producing food and repairing the collapsed infrastructure as well as demobilizing disloyal soldiers and locking up the guns. There will still be LOTS of trouble, but it should be manageable even with the indecision of Kaiser Karl. The reduction of brigandage by increasing food supply and returning men to work instead of war will ease many tensions, but not all.
Eventually, once it is clear that the Austro-Hungarians are going to stick around until the war ends instead of collapsing the Allies might very well cut a deal to get her to drop out and switch sides, something Karl might want to do given the pressure he is under and the increasingly bad end that Germany is coming to. The Hungarians will take the opportunity to husband their power for the break up of the two nations at the end of the war, but are still likely to be more stabile than historical, as the end of combat and return of basic necessities will limit the influence of the communists there. Expect a break of Austria and Hungary with a series of revolts from ethnic minorities and outsides states trying to take advantage.