If a 1914 otl-style WW1 occured despite the butterflies of eliminating the Italo-Ottoman and the 2 Balkan Wars, it might look like this:
1914: The Western and Eastern Fronts would proceed as in otl. Italy would stay neutral (or join the Entente without manpower and resource losses to the and gains from the Ottoman Empire, in this case, the Austro-Hungarian 5th Army would move from Serbia to Italy as in otl but a year early and the Austro-Hungarian 2nd Army would stay in Serbia longer to replace the 5th Army in the failure of invading Serbia before being moved to the Eastern Front as in otl but later in 1914). After the Ottomans joined the Central Powers, they would perform as well as otl for that year, except for Bulgarian and Greek invasions that year of the Ottoman Empire for the Entente, which would cost the Ottoman Empire Albania and Macedonia plus any advantages of having an initial connection with Austria-Hungary. Any Serbian reduction in strategic depth and population could be compensated by not having to defend Serbian Macedonia from Bulgaria with Bulgarian Macedonia being Serbian aligned rather than obtained from fighting with Serbia.
1915: The Western and Italian Fronts would proceed as in otl. In the Balkans, the Bulgarians and Greeks would rout the Ottomans from Thrace and the Aegean mainland coast respectively, stopping at Edirne for Bulgaria and Dedeagatch for Greece. The Anzac troops would do an invasion of Libya instead of Gallipoli for April 1915 and Suvla Bay in September 1915 together with the first Gallipoli landings. Despite the failure of both landings, the ammunition shortage produced by the landings and the delays in the landings would cause the Ottomans to lose troops at Gallipoli and Suvla and retreat to Catalca. The German 11th Army (and the otl Austro-Hungarian troops sent to the Trentino) would rout the Russians even more at Gorlice-Tarnow, which would be stopped from Estonia to Ukrainian Galicia by Russia transferring troops to Estonia from Ukrainian Galicia and from the Caucasus to Ukrainian Galicia and by Russia ordering the Gallipoli Campaign to be intensified to prevent the Ottomans from taking advantage of relocated Russian troops to invade the Caucasus, which was further aided by Ottoman ammunition shortages at Gallipoli and Suvla.
1916: The Western and Italian Fronts would proceed as in otl. On the Eastern Front, the German 11th Army and the Russian Caucasus Army would stay at Estonia longer. The Austro-Hungarian diversion of troops to the Trentino would result in the Brusilov Offensive proceeding as in otl and Romanian entrance into WW1 as in otl despite different Russian troops and the frontline being further from Lvov, Przemysl and the Carpathians. The still intact and surviving Serbia would be forced on the defensive due to typhus and army losses. The Romanians wouldn't have to rely on Russians to fight the Bulgarians and the Ottomans, but wouldn't have the Russian troops to prevent Romanian defeat nor to reinforce the Romanians against Germany and Austria-Hungary. The Ottomans end up being knocked out of WW1 by November 1916, after a resumed Dardanelles Naval Campaign in July 1916 destroyed Ottoman ships and railroads in Constantinople and tied up Ottoman troops at Constantinople.
1917: The Western and Italian Fronts would proceed as in otl. On the Eastern Front, the German 11th Army and the Russian Caucasus Army would stay at Estonia longer. The Romanians, without Russian aid, would be defeated more easily than otl and forced to surrender before the end of the year in August 1917. The defeated Ottomans would be carved up and garrisoned by the Entente. With the Serbs inactive, nothing active would happen in the Serbian Campaign for 1917. After Caporetto, Italy would be helped by Entente troops from the Western Front and the Middle Eastern Theatre.
1918: The Western Front would proceed as in otl. After the surrender of Russia and Romania, the German 11th Army would be transferred to the Western Front, but so would Entente troops fighting in the Middle East that year in otl and in Italy that year in this timeline. After failed invasions of Italy and Serbia, in September 1918, a joint Serb-Bulgarian-Greek offensive against Austria-Hungary would knock out Austria-Hungary from WW1 by 4 November 1918, aided by the Battle of Vittorio Veneto. The Middle East would be neutralised for that year other than Turkish and Iranian revolts against the Entente and the independence of Georgia, Armenia, Azerbaijan, the Hejaz including Jordan under the Hashemites and Saudi Arabia.
Remaining (unmentioned above) WW1 campaigns and fronts would proceed as in otl. The WW1 peace treaties would be similar to otl for Germany and Austria-Hungary (as split into Austria and Hungary). The WW1 peace treaty for Bulgaria would see Bulgaria on the winning side instead of being on the losing side and would see Bulgaria gaining Macedonia and some of Thrace (the latter would later be retaken by post-Ottoman Turkey from Edirne eastwards) while retaining the Western Outlands and Southern Dobruja (Bulgaria would lose its Aegean coast in that treaty as well, but in this timeline, because it never controlled its Aegean coast in the first place). The WW1 peace treaties for Turkey would be the same as in otl, but with Turkey losing land to Bulgaria, Serbia, Montenegro and Albania (permanently to the latter 3 nations without their land borders with Turkey), Libya to Britain and the Dodecanese to Greece and the Turks in the Dodecanese being included in the Greek-Turkish population exchange.
For the interwar period and WW2, the obvious difference to otl would be mandatory Bulgarian, Serbian and Montenegrin population exchanges with Turkey for Turks and Albanians, a slightly bigger and more satisfied Bulgaria (which might abandon its claims to the Aegean and Thrace in exchange for Greek and Turkish recognition of its rights to gain Macedonia and Dardanelles transit rights for Bulgarian ships) staying neutral and western European for WW2 and the Cold War (or Bulgaria might return to its otl Axis and Warsaw Pact alignment with predictable consequences), a British Libya to the extent of a "France fights on" scenario or to the extent of non-existent or failed amphibious landings in Libya and/ or Egypt and butterflying the Libyan portion of the North African Campaign in 1941-1943 with resulting consequences in the best case scenario for Britain or otl in the worst case scenario for Britain and a Dodecanese archipelago with fewer Turks there and spending more time under Ottoman Turkish rule and Greek rule (it might be captured by the Italians and the Germans simultaneously with the 1941 Battle of Crete or as in otl in its (Dodecanese) Campaign of 1943, with the Italians capturing it being more loyal to Germany than Italy).
