The idea is very nifty and I'll follow the thread with great interest, but IMO the end of the war in late 1918 just as in OTL is really too late, given the PoD. A CP Italy and a neutral America indeed all but ensures the final victory of the CPs but also significantly accelerates the collapse of Russia and France. You really should consider anticipating the end of the war to late 1917.
We also need a little more details about the course of the war: I assume Germany still goes Schliffen (otherwise no Entente Britain) and Italy does not enter the war immediately (otherwise France collapses in 1914). Therefore I assume Italy enters the war at the next optimal window in late Spring 1915, after negotiations to ensure her entry for the CPs are successful. The PoD most likey means that Germany is able to persuade A-H to cede Trento, Gorizia, and Trieste to Italy, and also that Italy has been promised pretty much all her claims against France (Nice, Savoy, Corsica, Tunisia, Djibouti, possibly even more French colonies). I also assume that Ottoman Empire and Bulgaria still enter the war for the CPs in pretty muuch as in OTL and the bloody fiasco of Gallipoli is already well underway when Italy attacks.
Main effects of the PoD: Italy will send an expeditionary force in Albania and Montenegro to backstab Serbia. The latter is encircled when Bulgaria attacks too and its Army is completely annihilated. This means no Entente expedition to Salonika and no split of Greece between pro-CP and pro-Entente governments. Greece is surrounded by CP powers so at the very least it stays an CP-friendly neutral. The Ottoman Empire is free to deliver more troops against the Russians and the British on other fronts. As a result, the OE fare better in the Caucasus and the Arab revolt either does not occur or is greately hampered. Once Serbia is killed, A-H is free to deliver the whole of their armies against Russia and Germany does not need to send as many troops to reinforce her, which may instead by used against France or better Russia (let's assume the latter since the CPs won). This significantly accelerates the schedule of Russian collapse by 6-12 months at the very least.
Moreover, a stronger CPs on the Eastern front and the Balkans might well mean that Romania does not enters for the Entente (if it does, it shall be crushed even more quickly than OTL) and either stays neutral or enters for the CPs. The latter would throw open the Ukraine front for the CPs and accelerate the Russian collapse by another season or so. So what does Romania do ITTL ?
Sweden too might choose to enter the war for the CPs as Russia seems losing if the CPs are able to play the "liberation of Finland" propaganda-diplomatic card well and promise Sweden substantial influence in post-war Finland. The intervention of CP Sweden too does accelerate the collapse of Russia by a season or so. Do they intervent ITTL ? Morevoer, there is a little known PoD you might easily use, besides CP Italy, to justify the CP victory ITTL. At the start of the war, the gung-ho Commander of the Russian Fleet sailed to deliver an ultimatum to the Swedish Fleet to vacate their bases on his own initative. Had not he be called back to the last minute, it is almost sure that a naval battle between Sweden and Russia would have resulted, and an enraged Sweden would have declared war on Russia. Neutral Sweden attacked by aggressive Russia would balance the propaganda and diplomatic effects of the "rape of Belgium" to a great degree among neutrals (esp. the USA).
America does not enter the war most likely because the stronger CP see victory at hand earlier (Russia collapses by 1916) so they never engage in unrestricted submarine warfare nor send the Zimmerman Telegram and the hand of the USA is never forced. Again, a CP Italy helps here and CP Sweden helps even more, esp. if you use the early PoD. Since Russia collapses earlier, do the Germans send Lenin to Russia or not, ITTL ? The lack of Lenin only delays Russia's military collapse by some months (the Russian Army had entered a death spiral of mutinies well before the Octrober Revolution) but radically changes the course of the Russian Revolution ITTL.
Italy's belligerance means they engage France in a mountain warfare on the Maritime Alps in late Spring 1915. Since Italian army is much better relatively to the French one in WWI than in WWII, they surely see initial limited success but fail to achieve a strategic breakthrough. France is in serious long-term trouble, however, as it is forced to deploy a substantial amount of Anglo-French troops on the Alps (the French Alps were nowhere as fortified as the Austrian Dolomites in 1915, so the Entente needs much more troops to stop the Italians than A-H OTL) and has a front stretching all the way from the English Channel to the Mediterranean, with only a pause on the Swiss border. Not good for limited French manpower reserves, especially when German and Italian High Commands start to syncronize their offensives on the Western front. Moreover, there are old standing Triple Alliance protocols to send part of the Italian Army to reinforce the German Army against France, which are reactivated now. This might ensure that any German offensive on the Western front (Verdun, anyone ?) sees much more success. Of course, such Italian troops could instead be used on the Belgian front or against Russia.
The Anglo-French could either go on the defensive on the Western Front (likely), which gives them a reprieve until Russia collapse, even if coordinated Italo-German offensives still consume much of their manpower, or try some big offensive a la Somme against the Germans or the Italians, which is a costly failure and comsumes their reserves even more. It is possible (but not really likely, after Gallipoli) that they try a landing against Italy in Sardinia or Sicily. The former might well succeed, but it does not seriously tack Italy's figthing ability. The latter is a costly failure rivaling Gallipoli. If the Entente still chooses to go on the offensive on the Western front, the French Mutinies still occur ITTL and are even more widespread, as France has suffered even more attrition thanks to Italy. Therefore, suppressing them without Germany and Italy noticing and going on the offensive becomes even more unlikely. Such an attack is a sure strategic breakthough for the CPs.
On the naval side, Italy's belligerance means that the Austrian/Italian/Ottoman fleets will eventually combine and make a worthy opponent for the Anglo-French fleets in the Mediterranean, which becomes an hotly contested area. This might or might not force the British to redeploy some ships to the Mediterranean, giving better chances to the HSF, ro they might concede it to a large degree (they almost surely do in the Eastern Med, owning to the pro-CP Greece). Depending on the precise balance of forces here, this may mean the French conquering Libya or the Italians getting Tunisa and making heavy inroads into Algeria.
Anyway, even assuming France somehow manages to hold out till after the collapse of Russia (which likely means Britain is forced to throw more and more of her own manpower in the French meatgrinder, hampering her ability to fight in other theaters, as against the Ottomans), the situation grows truly desperates after Russia goes Brest-Litovsk and the vast majority of the CPs armies are redeployed on the Western Front. Without the help of America, France by now is scraping the barrel of her manpower reserves and barely holding out thanks to the ever-greater committment of British manpower. The first coordinated Italo-German offensive sees a German strategic breakthorugh towards the Seine and a secondary Italian one towards the Rhone. The precise timetable of France's surrender is open to variations, but once they lose any of Paris, Lyon, and Marseilles, they are toast. Britain sees the writing on the wall and pleads for a compromise peace soon after the surrender of France. So does Japan.
Hence, Russia collapses by 1916 and France collapses by 1917. The Ottomans manage to snatch Baku, Kars, Adahan and Batum are returned. Ottomans gain control of Kuwait and Arabia, and a significant zone of influence in Persia.
Russia is most likely a chaotic revolutionary mess anyway, with civil war well underway. What really matters here is whether the victorious CPs have the fighting spirit still to wage a large scale intervention in the RCW and ensure the victory of a puppet Czarist regime. Since the war is shorter by about a year, they might well, or might not. Also, the possible absence of Lenin means that the Bolsheviks fail to seize power in Russian heartland and eventually trigger an insurgency in a much more patchwork feashion under the leadership of Trotzky, which means the defeat in the Civil War more likely.
Somebody needs to keep his history straight between the Kaiserreich and Nazi Germany, lest this TL really starts on the wrong foot. 