Lets say :
1. USA stays out of the war
2. The final Germany offensive succeeds in taking Aimens. GB pulls much of its military out, and France agrees for diplomatic peace. Germany has revolution in the air so agrees to many compromises.
3. BL in place in the east
4. AL pleb set for 1928 (10 years after war)
So alliance system of
CP : Germany, Ukraine, Bulgaria, AH, Turkey, Belgium, China, Finland, Sweden, Poland, Baltic States
Allies : France, GB, Italy, Japan, USSR, Greece, Romania, Serbia
War starts with USSR attacking Ukraine