No Italy in the war mean a very likely CP victory just not immediate 16/17, with a strong probabily of a B-L type of treaty with Russia and in the western an agreed cease fire with some term (like German get est-europe plus luxemburg and some influence in Belgium but lost all colonies) seeing more in detail:
USA: with Germany in a more favorable position and with a more stable method to lessen the blockade (Italy), there is a lot less need of issue the order of unrestricted submarine warfare and to sent the Zimmerman telegram so WW will not have any possibility to enter directely the war. The liberticide set of law will be avoided and we get an USA where the socialist party and the German culture is still existent. Wilson can try to play the peacemaker during the negotiation but here is idea will probably discarted immediately.
Russia: Lenin is probably butterflied away but a Brest-Litovosk like treaty no (almost certain something of less crippling but not that much). In the long term Russia will probably be a Weimar Republic analogue for economic and political stability, strong possibility of a dictatorship.
A-H: one of the big loser even in case of CP victory, is time is come and the fact is exacerbated by a clueless and fearfull leadership and naturally by all the death, debit and the crippled economy due to the war. When the renegotiation with Hungary is due nothing short of a miracle can save the empire, Germany can prop them for a time but she has her problem and the new east europe nation to save, so after a while Berlin will left his ally alone. How things go is really nebulos, can be a pacific break up like the OTL URSS or a full fledged civil war; Romania and Italy will surely jump at the occasion to get some land at the Hasburg expense, Germany will go to reluctantely absorb the German land of the Empire (included the Czech) and to get control of the successor nations like Croatia and Slovakia. Hungary can really descend in a civil war after the break up due to the influx of communist ideology, the strife of war and a leadership just out of feudalism.
Serbia and Montenegro: can try to recover what lost in the war plus some other bits of territory and throw out the puppet leader the victorious CP put in charge.
UK: get a white peace as the German can't do very much to enforce harsh terms, political unrest is in the future when the cost of the lost war (monetary and human) will be fully understand.
France: some serius civil and political problem in the future, fascism will probably arise here and will try the revanchist way.
Germany: lost colonies, get east-europe and must prop that goverment for a while, some political unrest at home due to the fact that the time of the kaiser as political ruler si over and a serious reform is unavoidable.
Italy and Romania: stay neutral and contrary to the common sense of the time they greatly beneficied from that, by commercing with the CP and by getting territory from the corpse of A-H when she implode. Italy here has time and resource to take full control of Lybia by the time of the end of the war.