Given that two major politicians of the 20th century fought in WW1, of whom one was socialist before, and both joined an irredentist fascist movement, Stalin might end as head of a nationalist Russian party.
Mussolini had rejected the Italian Socialist Party's antiwar position early in the war. Stalin in his years of exile seems always to have maintained a Bolshevik antiwar position. Note his letter to Lenin in 1915:
"My greetings to you, dear Ilyich, warm, warm greetings. Greetings to Zinoviev, greetings to Nadezhda Konstantinovna. How are you, how is your health? I live as before, chew my bread, completing half of my term. It is rather dull, but it can't be helped. But how are things with you? It must be much livelier where you are. I recently read Kropotkin's articles—the old fool must have completely lost his mind. I also read a short article by Plekhanov in *Rech*—an incorrigible old gossip. Ekh-mah! And the Liquidators with their deputy agents of the Free Economic Society? There's no one to beat them, the devil take me! Is it possible that they will get away with it and go unpunished? Make us happy and let us know that in the near future a newspaper will appear that will lash them across their mugs, and do it regularly, and without getting tired. If it should occur to you to write, do so to the address: Turukhan Territory, Yeniseisk Province, Village Monastyrskoye, for Suren Spandaryan. Your Koba. Timofei [Spandaryan] asks that his sour greetings be conveyed to Guesde, Sembat and Vandervelde on their glorious—ha-ha—post of ministers."
https://books.google.com/books?id=6ZNuZ6fq1WoC&pg=PA625 The people Stalin is ridiculing are precisely the socialists who had gone over to the "patriotic" side.
Now you might say, would serving in the military change Stalin's mind? But remember that it was only late in the war that the Tsarist government felt desperate enough to start drafting exiled revolutionaries, and it was only in December 1916 that he was rejected for military service because of his arm. So even if he was drafted in December 1916 he would have only a couple of months of service before the February Revolution would break out. And after the February revolution, right-wing nationalist positions were *very* unpopular among Russian soldiers...