Say that the Bolsheviks had signed the original treaty (which was sooooo much less harsh, too), because Lenin's idea of the need for an immediate peace prevails, how would the Germans do on the Western Front in 1918 now that the Eastern Front would be secure by Christmas 1917?
Likely not enough extra time to win, but could it delay the end of the war? If the war lasts until 1919, might the radical Bolshevik idea that the imperialists were on the verge of revolution come true?