Based upon the OP of Italy joining, whether politically viable or not, Italy has several problems. First, the Libyan pacification is ongoing, slowly and poorly. Second, the Italian Army is small, with minimal artillery. Third, the logistical tail for the army is minimal.
Positively, the army has recent combat experience. The navy had learned several valuable lessons from the Turkish War, and is building more advanced vessels. The Army/Navy split has not developed as in WW2. The Navy had experienced the use of aircraft in combat conditions.
The Italians will spend most of 1914 building and training its Army. The Navy has some capability to start the war. The French, Montenegrin and Serbian allies would welcome any help in 1914 and 1915. Even minor assistance to the Lovcen battles. in OTL September to October 1914 artillery duels. would improve Montenegrin resolve and allow some reinforcement to Serbia. The inactivity of the Italian surface fleet, especially the battleships, exacerbated the Army/Navy rivalry post war. The deployment of the battle fleet and a division of experienced troops in September of 1914 would have gone far to force the AH forces to re-evaluate their southern front, further stretching resources. Anything keeping Serbia in the war delays Bulgarian involvement. Italian involvement may actually increase Turkish desires to join to regain the Aegean isles. I doubt Turkey would be in any shape to influence the Balkan campaigns beyond a Russian blockade, unless attacked.