Russia by 1915 survived on the prestige of the army, mostly. That prestige existed despite the losses against the Germans because the Russian army was doing well against the Ottomans and had gutted the Austro-Hungarians.
If the Austro-Hungarians are not gutted, the Russians will need to get more troops against them (especially if they had more losses themselves) which will mean only holding in the Caucasus and far less prestige for the army. I could see an upheaval coming early 1916, probably a Kerenskij-like government taking over, committed to continuing the war (pressured by the Entente), but with the army more or less disintegrating by late 1916, like OTL mid-1917.
I think the Romanians could join after a Gorlice-Tarnow equilent summer 1915, thinking the Russians are done for (they joined the Entente after the Brusilov Offensive, thinking Austria-Hungary was done for).
I do not think Italy will join when it did ITTL, if Austria-Hungary still looks strong. They might still do it, but by 1916, they are facing all of Austro-Hungary's might - and they are very close to the best infrastructure and most loyal and industrialised Austrian lands, which means the Austro-Hungarians will easily be able to throw lots at the Italians.
If the Austro-Hungarians are not gutted, the Russians will need to get more troops against them (especially if they had more losses themselves) which will mean only holding in the Caucasus and far less prestige for the army. I could see an upheaval coming early 1916, probably a Kerenskij-like government taking over, committed to continuing the war (pressured by the Entente), but with the army more or less disintegrating by late 1916, like OTL mid-1917.
I think the Romanians could join after a Gorlice-Tarnow equilent summer 1915, thinking the Russians are done for (they joined the Entente after the Brusilov Offensive, thinking Austria-Hungary was done for).
I do not think Italy will join when it did ITTL, if Austria-Hungary still looks strong. They might still do it, but by 1916, they are facing all of Austro-Hungary's might - and they are very close to the best infrastructure and most loyal and industrialised Austrian lands, which means the Austro-Hungarians will easily be able to throw lots at the Italians.