Any notion that Italy was serious about potentially joining the Central Powers is completely misguided. Salandra’s government was actually worried that the Austrians might provide major concessions to Italy because the press was already so anti-Austrian and whipping the middle class into a frenzy demanding war against Austria, and Italy had already made serious promises to France and Britain. The military may have had plans for all sorts of eventualities, the same way that I’d bet the Pentagon has some dusty old plan for invading Mexico that no one would ever seriously use as evidence of aggressive intent, but it was clear from the beginning who the enemy was going to be.
As I mentioned earlier, the only reason Italy even entered the Triple Alliance was because after the crushing French defeat in the Franco-Prussian War, Italy wanted to have Bismarck on her side, and saw Germany as a valid counterweight to Austria. Because Bismarck had no interest in the Balkans (cf. his famous quote about them not being worth the bones of a single grenadier), Italy and Germany saw eye to eye while Bismarck was in power. However, as soon as Bismarck left and German foreign policy changed in a variety of ways (all of which were to prove disastrous for Germany in the end), favoring Austria over Russia and alienating Italy in the process. From that instant, Italy was looking for ways to graciously bow out of its Triple Alliance. Giolitti, Salandra - basically, every government of every stripe - all were trying to realign Italy with the traditional ally, France. The only issue was whether or not Italy would join the war. The “notabili” seemed to want to stay out, but due to changes in Italian voting laws party politics were beginning to count for more than personalities.
I’m sure there’s some author out there who has tried to make the case that Italy might have stayed out, because of course that’s the nature of academia. However, I haven’t seen any respected or compelling arguments to that effect. In addition to Montanelli (his 22-volume history of Italy is truly epic), reading Martin Gilbert’s history of the war, or Hew Strachan, or any of the other noted historians of the war, will quickly impress upon the reader the impossibility that Italy would join the war as an ally of Austria.